Exhaust gas treatment system and model for controlling hydrocarbon adsorption / desorption in a hydrocarbon trap

Abstract

An exhaust gas treatment system including a hydrocarbon storage model and a controller operatively connected to the hydrocarbon storage model, the controller configured to perform a method for determining a hydrocarbon storage level of a hydrocarbon trap, the method comprising determining a first reaction rate representing a hydrocarbon adsorption rate at non-acidic sites of the hydrocarbon trap, determining a second reaction rate representing a hydrocarbon desorption rate at non-acidic sites of the hydrocarbon trap, determining a third reaction rate representing a hydrocarbon adsorption rate at acidic sites of the hydrocarbon trap, determining a fourth reaction rate,which represents a hydrocarbon desorption rate at acidic sites of the hydrocarbon trap and comprises determining the hydrocarbon storage level in the hydrocarbon trap based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

Description

INTRODUCTION

[0001] The subject matter disclosure relates to exhaust emission control systems of internal combustion engines and, in particular, to minimizing hydrocarbon emissions during cold starting of engines.

[0002] Such systems and methods for exhaust gas purification are known, for example, from US 6,477,831 B1, US 6,029,441 A, and US 2019 / 0 353 068 A1. Further prior art is the publication by KOLTSAKIS, Grigorius, and STAMATELOS, Anastasios: Modeling of Hydrocarbon Trap Systems; SAE Paper 200-01-0655; SAE 2000 World Congress, Michigan, March 6-9, 2000.

[0003] Exhaust gases emitted by an internal combustion engine are a heterogeneous mixture containing gaseous emissions such as carbon monoxide (“CO”), unburned hydrocarbons (“HC”) and nitrogen oxides (“NO xMany of these emission components are highly regulated. Catalyst components, typically disposed on catalyst supports or substrates, are provided in engine exhaust systems as part of an aftertreatment system to convert some or all of these exhaust components into unregulated compounds.

[0004] An exhaust treatment system typically includes one or more catalyst-based treatment devices, such as a three-way catalyst (TWC). The function of a catalyst, such as a TWC, is to convert primary emissions from the engine into carbon dioxide, water, and nitrogen. For the catalyst or TWC to function as an effective catalyst for hydrocarbon oxidation, it is required to achieve a high operating temperature, which can be difficult during cold-start conditions. Therefore, hydrocarbon traps (HCTs) are commonly used to store hydrocarbons during cold start and release the hydrocarbons when the catalyst or TWC has reached a sufficient temperature.However, the HCT may reach a temperature where it releases hydrocarbons before the catalyst or TWC has reached a sufficient temperature for catalytic oxidation of the hydrocarbon species, resulting in inefficient and / or insufficient hydrocarbon oxidation.

[0005] Accordingly, it is desirable to provide sufficient time for the catalyst or TWC to reach operating temperature before the majority of hydrocarbon pollutants enter the catalytic system. SUMMARY

[0006] To solve this problem, an exhaust gas treatment system with the features of claim 1 and a method according to claim 6 are provided. Further advantageous embodiments of the invention can be found in the dependent claims, the description, and the accompanying drawings.

[0007] The exhaust gas treatment system according to the invention includes a first catalyst located downstream of an exhaust outlet of an internal combustion engine, the first catalyst receiving exhaust gas discharged from the exhaust outlet. A hydrocarbon trap is located downstream of the first catalyst, the hydrocarbon trap receiving exhaust gas discharged from the first catalyst. An air injection port is configured to supply an airflow upstream of the hydrocarbon trap and downstream of the first catalyst. An exhaust gas heating unit is located downstream of the hydrocarbon trap, the exhaust gas heating unit receiving exhaust gas discharged from the hydrocarbon trap. A second catalyst is located downstream of the exhaust gas heating unit, the second catalyst receiving exhaust gas discharged from the exhaust gas heating unit.The exhaust treatment system further includes a hydrocarbon storage model and a controller operatively connected to the hydrocarbon storage model, the controller configured to perform a method for determining a hydrocarbon storage level of the hydrocarbon trap.The method for determining a hydrocarbon storage level of the hydrocarbon trap includes determining a first reaction rate representing a hydrocarbon adsorption rate at non-acidic sites of the hydrocarbon trap, determining a second reaction rate representing a hydrocarbon desorption rate at non-acidic sites of the hydrocarbon trap, determining a third reaction rate representing a hydrocarbon adsorption rate at acidic sites of the hydrocarbon trap, and determining a fourth reaction rate representing a hydrocarbon desorption rate at acidic sites of the hydrocarbon trap.The hydrocarbon storage level in the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0008] According to another embodiment, the controller is further configured to adjust an aftertreatment operation on the hydrocarbon released by the hydrocarbon trap based on the hydrocarbon storage level, a net reaction rate of hydrocarbon desorption from the hydrocarbon trap, or a combination thereof. The net reaction rate of hydrocarbon desorption from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0009] According to another embodiment, the step of adjusting the aftertreatment operation includes selectively operating the exhaust gas heating unit, selectively supplying an air flow at the air injection port, or a combination thereof.

[0010] According to another embodiment, the exhaust gas treatment system further includes a first temperature sensor for determining a temperature of the hydrocarbon trap.

[0011] According to a further embodiment, the exhaust gas treatment system further includes a second temperature sensor for determining a temperature of the second catalyst.

[0012] According to a further embodiment, the first reaction rate is represented by equation 1: rads=[HC]θZA1Zexp(EaZ−RT), the second reaction rate is represented by equation 2: rdes=θZHCA−1Zexp(EaZ+ΔHZ−RT), the third reaction rate is represented by equation 3: rads=[HC]θZHA1ZHexp(EaZH−RT), and the fourth reaction rate is represented by equation 4: rdes=θZHHCA−1ZHexp(EaZH+ΔHZH−RT), where in equations 1 to 4 [HC] is a concentration of the hydrocarbon by the hydrocarbon trap, θ Z is a site density of the acid-free sites of the hydrocarbon trap that are not bound by hydrocarbon, θ ZHC is a site density of the acid-free sites of the hydrocarbon trap that are bound by hydrocarbon, θ ZH is a site density of the acidic sites of the hydrocarbon trap that are not bound by hydrocarbon, θ ZHHC is a site density of the acidic sites of the hydrocarbon trap that are bound by hydrocarbon, A 1Zis a pre-exponential factor of the acid-free sites of the hydrocarbon trap for hydrocarbon adsorption, A -1Z is a pre-exponential factor of the acid-free sites of the hydrocarbon trap for hydrocarbon desorption, A 1ZH is a pre-exponential factor of the acidic sites of the hydrocarbon trap for hydrocarbon adsorption, A -1ZH is a pre-exponential factor of the acidic sites of the hydrocarbon trap for hydrocarbon desorption, Ea z is an activation energy of an adsorption reaction at the acid-free sites of the hydrocarbon trap, Ea zH is an activation energy of the adsorption reaction at the acidic sites of the hydrocarbon trap, ΔH Z is a hydrocarbon adsorption heat at the acid-free sites of the hydrocarbon trap, ΔH ZHis a hydrocarbon adsorption heat at the acidic sites of the hydrocarbon trap, R is the universal gas constant, and T is the temperature.

[0013] According to a further embodiment, the exhaust gas heating unit is selectively operated when a net reaction rate of hydrocarbon desorption from the hydrocarbon trap is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0014] According to a further embodiment, the air stream is selectively supplied to the air injection port when a net reaction rate of hydrocarbon desorption from the hydrocarbon trap is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0015] According to a further embodiment, an amount of air supplied at the air injection opening is proportional to a calculated oxygen deficiency at the second catalyst.

[0016] The inventive method includes operating the internal combustion engine to provide an exhaust fluid at an exhaust outlet of the internal combustion engine; and directing the exhaust fluid through an exhaust treatment system. The exhaust treatment system includes a first catalyst located downstream of the exhaust outlet of the internal combustion engine, the first catalyst receiving exhaust gas output from the exhaust outlet. The exhaust treatment system includes a hydrocarbon trap located downstream of the first catalyst, the hydrocarbon trap receiving exhaust gas output from the first catalyst. The exhaust treatment system includes an air injection port configured to deliver an airflow upstream of the hydrocarbon trap and downstream of the first catalyst.The exhaust treatment system includes an exhaust heating unit located downstream of the hydrocarbon trap, the exhaust heating unit receiving exhaust gas output from the hydrocarbon trap. The exhaust treatment system includes a second catalyst located downstream of the exhaust heating unit, the second catalyst receiving exhaust gas output from the exhaust heating unit. The exhaust treatment system also includes a hydrocarbon storage model and a controller operatively connected to the hydrocarbon storage model, the controller configured to perform a method for determining a hydrocarbon storage level of the hydrocarbon trap.The method further includes determining a first reaction rate representing a hydrocarbon adsorption rate at non-acidic sites of the hydrocarbon trap, determining a second reaction rate representing a hydrocarbon desorption rate at non-acidic sites of the hydrocarbon trap, determining a third reaction rate representing a hydrocarbon adsorption rate at acidic sites of the hydrocarbon trap, and determining a fourth reaction rate representing a hydrocarbon desorption rate at acidic sites of the hydrocarbon trap. The method further includes determining the hydrocarbon storage level in the hydrocarbon trap based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0017] According to another embodiment, the method further includes adjusting an aftertreatment operation on the hydrocarbon released by the hydrocarbon trap based on the hydrocarbon storage level, a net reaction rate of hydrocarbon desorption from the hydrocarbon trap, or a combination thereof, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0018] According to another embodiment, the step of adjusting the aftertreatment operation includes selectively operating the exhaust gas heating unit, selectively supplying an air flow at the air injection port, or a combination thereof.

[0019] According to a further embodiment, in the method for treating an exhaust gas from an internal combustion engine in a motor vehicle, the first reaction rate is represented by equation 1: rads=[HC]θZA1Zexp(EaZ−RT), the second reaction rate is represented by equation 2: rdes=θZHCA−1Zexp(EaZ+ΔHZ−RT), the third reaction rate is represented by equation 3: rads=[HC]θZHA1ZHexp(EaZH−RT), and the fourth reaction rate is represented by equation 4: rdes=θZHHCA−1ZHexp(EaZH+ΔHZH−RT), where in equations 1 to 4 [HC] is a concentration of hydrocarbon by the hydrocarbon trap, θ Z is a site density of the acid-free sites of the hydrocarbon trap that are not bound by hydrocarbon, θ ZHCis a site density of the acid-free sites of the hydrocarbon trap that are bound by hydrocarbon, θ ZH is a site density of the acidic sites of the hydrocarbon trap that are not bound by hydrocarbon, θ ZHHC is a site density of the acidic sites of the hydrocarbon trap that are bound by hydrocarbon, A 1Z is a pre-exponential factor of the acid-free sites of the hydrocarbon trap for hydrocarbon adsorption, A -1Z is the pre-exponential factor of the acid-free sites of the hydrocarbon trap for hydrocarbon desorption, A 1ZH is a pre-exponential factor of the acidic sites of the hydrocarbon trap for hydrocarbon adsorption, A -1ZH is a pre-exponential factor of the acidic sites of the hydrocarbon trap for hydrocarbon desorption, Ea zis an activation energy of an adsorption reaction at the acid-free sites of the hydrocarbon trap, Ea zH is an activation energy of the adsorption reaction at the acidic sites of the hydrocarbon trap, ΔH Z is a hydrocarbon adsorption heat at the acid-free sites of the hydrocarbon trap, ΔH ZH is a hydrocarbon adsorption heat at the acidic sites of the hydrocarbon trap, R is the universal gas constant, and T is the temperature.

[0020] According to another embodiment, the method further includes operating the exhaust gas heating unit when a net reaction rate of hydrocarbon desorption from the hydrocarbon trap is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0021] According to a further embodiment, the exhaust gas heating unit is not operated when the net reaction rate of hydrocarbon desorption from the hydrocarbon trap is zero.

[0022] According to another embodiment, the method further includes supplying the air stream at the air injection port when a net reaction rate of hydrocarbon desorption from the hydrocarbon trap is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0023] According to a further embodiment, in the method for treating an exhaust gas from an internal combustion engine in a motor vehicle, an amount of air supplied at the air injection opening is proportional to a calculated oxygen deficiency at the second catalyst.

[0024] According to a further embodiment, in the method for treating an exhaust gas from an internal combustion engine in a motor vehicle, the air flow is not supplied until the hydrocarbon trap has reached a hydrocarbon desorption temperature.

[0025] According to a further embodiment, in the method for treating an exhaust gas from an internal combustion engine in a motor vehicle, the air flow is not supplied before the second catalyst has reached a hydrocarbon oxidation temperature.

[0026] According to a further embodiment, in the method for treating an exhaust gas from an internal combustion engine in a motor vehicle, the air flow is not supplied when the net reaction rate of hydrocarbon desorption from the hydrocarbon trap is zero.

[0027] The above features and advantages and other features and advantages of the disclosure are readily apparent from the following detailed description when considered in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Further features, advantages and details appear in the following detailed description only as examples, whereby the detailed description refers to the drawings; they show: Fig. 1 a motor vehicle including an internal combustion engine and an emissions control system according to one or more embodiments; Fig. 2 is a schematic plan view of an exhaust gas treatment system according to one or more embodiments; Fig. 3 is a flowchart of an illustrative method according to one or more embodiments; Fig. 4 is a flowchart of an illustrative method according to one or more embodiments; Fig. 5A is a graph of hydrocarbon (HC) concentration (parts per million, ppm) versus time (seconds, s) as measured at the inlet of a hydrocarbon trap and at the outlet of a hydrocarbon trap, and temperature (°C) versus time (s) as measured at the inlet of the hydrocarbon trap and at the second catalyst, according to one or more embodiments; and Fig. 5B is a graph of surface coverage of the hydrocarbon trap material versus time (s) as measured for the acidic and non-acidic sites of the hydrocarbon trap material, and temperature (°C) versus time (s) as measured at the hydrocarbon trap inlet and the second catalyst, according to one or more embodiments. DETAILED DESCRIPTION

[0029] The following description is merely exemplary and is not intended to limit the present disclosure, its applications, or uses.

[0030] Hydrocarbon traps (HCTs), such as those using zeolites as hydrocarbon capture components, have been investigated for cold-start hydrocarbon control (CTC). In these systems, the molecular sieve zeolite component adsorbs and stores hydrocarbons during the startup period, rapidly releasing the stored hydrocarbons when the exhaust temperature is high enough to desorb hydrocarbons. The desorbed hydrocarbons are then converted by a hydrocarbon oxidation catalyst, such as a three-way catalyst (TWC) component, downstream of the HCT. However, during a cold start, HCTs may reach the hydrocarbon desorption temperature (HCT) before the TWC has reached a suitable temperature for HC oxidation, even when an exhaust heater (EH) is used to warm the TWC.As disclosed herein, air injection downstream of a first catalyst and upstream of a hydrocarbon trap according to a specific schedule provides a cooling effect on the HCT to delay the release of hydrocarbons from the HCT, allowing additional time for the EH to warm the TWC to a suitable operating temperature for hydrocarbon oxidation. The cooling effect of air injection upstream of the HCT may also serve to maximize a temperature differential between the HCT and the second catalyst, thereby improving hydrocarbon oxidation efficiency.

[0031] The internal combustion engine generally represents any device that can produce an exhaust stream containing gaseous (e.g. NO x , CO x, O2) and / or particulate matter species, and the disclosure herein should accordingly be interpreted as applicable to all such devices. As used herein, "off-gas" refers to any chemical species or mixture of chemical species that may require treatment and includes gaseous, liquid, and / or solid species. An off-gas stream may, for example, be a mixture of one or more NO x -grades, one or more liquid hydrocarbon (HC) grades, carbon dioxide, and / or carbon monoxide. It should further be recognized that the embodiments disclosed herein may be applicable to the treatment of effluent streams that do not include carbonaceous and / or particulate grades. The exhaust particulates generally include carbonaceous soot and other solid and / or liquid carbonaceous grades.

[0032] According to an exemplary embodiment, an exhaust treatment system for a motor vehicle is provided. In Fig. 1, a motor vehicle 10 is shown in the form of a light truck. It should be appreciated that the motor vehicle 10 may take various forms, including passenger cars, commercial transports, watercraft, and the like. The motor vehicle 10 includes a body 12 having an engine compartment 14 and optionally a passenger compartment 15 and / or a cargo bed 17. The engine compartment 14 contains an internal combustion engine 24. The internal combustion engine 24 includes an exhaust system 30 fluidly connected to an exhaust treatment system 34. The internal combustion engine 24 may also be connected to other engine components 26. The exhaust gases produced by the internal combustion engine 24 flow through the exhaust treatment system 34 to reduce and / or convert emissions that may exit through an exhaust pipe 36 to the ambient atmosphere.

[0033] While the Fig. 1 is shown as the sole primary power source of the vehicle 10, it may also represent a second primary engine source used in conjunction with another primary power source, such as in an electric motor of a hybrid.

[0034] According to one aspect and as in Fig. 2, a system 200 is provided that includes an internal combustion engine 201 having an exhaust outlet 203, wherein the internal combustion engine 201 delivers an exhaust gas stream via the exhaust outlet 203. The internal combustion engine 201 may include one or more exhaust outlets 203. Fig. 2, for example, shows a pair of exhaust outlets 203 for conducting combustion gases from the internal combustion engine 201.

[0035] A first catalyst (e.g., a first three-way catalyst or TWC) 205 is provided downstream of the exhaust outlet 203. The first catalyst 205 is in fluid communication with the exhaust outlet 203 to receive an exhaust gas output (exhaust stream) from the exhaust outlet 203 of the internal combustion engine 201.

[0036] The first catalyst 205 may be one of various flow-through catalyst devices that oxidize both CO and hydrocarbons and NO xcan reduce. According to some embodiments, the first catalyst 205 may include a flow-through metal or ceramic monolith substrate. The substrate may be disposed in an assembly within a stainless steel shell or container having an inlet in fluid communication with the exhaust outlet 203 and an outlet in fluid communication with an exhaust conduit 207. The substrate may include a catalyst compound disposed thereon. The catalyst compound may be applied as a washcoat and may include platinum group metals, such as platinum (Pt), palladium (Pd), rhodium (Rh), or other suitable oxidation catalysts, or a combination thereof. A washcoat layer includes a compositionally distinct material layer disposed on the surface of the monolithic substrate or an underlying washcoat layer.A catalyst may contain one or more washcoat layers, where each washcoat layer may have distinct chemical catalytic functions. For the first catalyst 205, the catalyst compositions for the oxidation and reduction functions may be located in discrete washcoat layers on the substrate, or alternatively, the compositions for the oxidation and reduction functions may be located in discrete longitudinal zones on the substrate.

[0037] The exhaust treatment system 200 includes a hydrocarbon trap (HCT) 209 located downstream of the first catalyst 205. The HCT 209 is in fluid communication with the first catalyst 205 and receives exhaust gas output from the first catalyst 205. As mentioned herein, the first catalyst 205 may be in fluid communication with the HCT 209, for example, via a segment of the exhaust conduit 207.

[0038] Suitable HCT storage materials for hydrocarbons contain microporous solids, so-called molecular sieves, with a zeolitic material representing a suitable microporous solid for capturing HC. The storage materials, such as zeolitic (or zeotypic) materials, have a porosity suitable for storing or capturing hydrocarbons at least until a target desorption temperature is reached. This means that the hydrocarbons are adsorbed while the exhaust gas is cold (e.g., during a cold start) and desorbed when a higher exhaust temperature is reached. Zeolites are microporous crystalline aluminosilicate materials characterized by well-ordered 3D structures with uniform pore / channel / cage structures, e.g.3 to 12 Å or 3 to 10 Å (depending on the framework type) and the ability to undergo ion exchange to allow the distribution of catalytically active cations throughout the structure. Zeotypes are structural isotypes / isomorphs of zeolites, where, instead of a framework derived from connected silica and alumina tetrahedra, the zeotypes are based, for example, on alumina-phosphate (ALPO), silica-alumina-phosphate (SAPO), metal-alumina-phosphate (M-ALPO), or metal-silica-alumina-phosphate (M-APSO). Exemplary zeolitic materials include, for example, mordenite (MOR), Y-zeolites (FAU), ZSM-5 (MFI), β-zeolites (BEA), or combinations thereof. These are preferably used in H form or NH4 form, where they are exchanged with transition metals.

[0039] The exhaust treatment system 200 includes an exhaust heating unit 213 located downstream of the HCT 209. The exhaust heating unit 213 is in fluid communication with the HCT 209 and receives exhaust gas output from the HCT 209. As mentioned herein, the exhaust heating unit 213 may be in fluid communication with the HCT 209, for example, via a segment of the exhaust conduit 207. Any suitable exhaust heating unit 213 may be used. The exhaust heating unit 213 may be, for example, an electric heater. If the vehicle is a conventional vehicle powered only by the internal combustion engine 201, the exhaust heating unit 213 is powered by the engine 201 after cranking (i.e., post-cranking heating after the engine 201 has been started).If the vehicle is a hybrid vehicle powered by either the internal combustion engine 201 and / or a separate ICE / electric motor combination (not shown), then the exhaust heating unit 213 may be powered by either the engine 201 or the ICE / electric motor combination.

[0040] The exhaust treatment system 200 includes a second catalyst (e.g., a second TWC) 215 located downstream of the exhaust heating unit 213. The second catalyst 215 is in fluid communication with the exhaust heating unit 213 and receives exhaust gas output from the exhaust heating unit 213. As mentioned herein, the second catalyst 215 may be in fluid communication with the exhaust heating unit 213, for example, via a segment of the exhaust conduit 207. The second catalyst 215 may be one of various flow-through catalyst devices that both oxidize CO and HCs and oxidize NO xcan be reduced, using any suitable catalyst, such as those described herein for the first catalyst 205.

[0041] The exhaust treatment system 200 includes an air injection port 211 configured to selectively deliver an airflow upstream of the HCT 209 and downstream of the first catalyst 205. The location of the air injection port 211 is not particularly limited. According to some embodiments, the airflow may be combined with the exhaust gas output from the first catalyst 205 at a location immediately adjacent to the outlet of the first catalyst 205. According to other embodiments, the air injection port 211 may be located immediately adjacent to the inlet of the HCT 209.

[0042] The air injection source may be provided by an auxiliary pump or may be tapped from the engine's compressor via a valve and / or throttle. For vehicles with a turbocharger, boost pressure and turbocharged air may be used as the source. According to other embodiments, the air source may be from the crankcase, using the energy generated therein to provide the air injection. According to some embodiments, the air source may be a supercharger compressor or another air pumping device included in the engine.

[0043] A technical challenge associated with the use of an HCT system 209 is determining the status or inventory level of the HCT unit 209 and the rate at which the HCs are released from the HCT 209. In particular, the use of the electric heater and / or air injection should be optimally tied to the status of the HCT unit (HC inventory) and the predicted release profile of the hydrocarbons as a function of time and temperature. The exhaust treatment system further includes a hydrocarbon storage model (not shown) and a controller 217 operatively connected to the hydrocarbon storage model. The controller 217 is configured to perform a method for determining the hydrocarbon storage level of the HCT 209.The controller 217 may then activate or operate the HER 213, supply the airflow upstream of the HCT 209, or a combination thereof based on the hydrocarbon storage level of the HCT 209, as described in more detail herein.

[0044] The method for determining the hydrocarbon storage level of the HCT 209 includes determining a first reaction rate representing a hydrocarbon adsorption rate at non-acidic sites of the HCT 209; determining a second reaction rate representing a hydrocarbon desorption rate at non-acidic sites of the HCT 209; determining a third reaction rate representing a hydrocarbon adsorption rate at acidic sites of the HCT 209; determining a fourth reaction rate representing a hydrocarbon desorption rate at acidic sites of the HCT 209; and determining the hydrocarbon storage level in the HCT 209 based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0045] Determining the first, second, third, and fourth reaction rates can use a dual-site hydrocarbon trap (acidic / acidic sites) modeling approach to determine the adsorption and desorption volume behavior of the hydrocarbon species. The model assumes two main interactions between the HCT material and the hydrocarbon. The first is HC storage within, for example, the pores of the zeolite material, referred to as the acidic sites of the HCT material. The second is HC interaction with, for example, the Brønsted acid sites of the zeolite material, referred to as the acidic sites of the HCT material.Consequently, the combination of the first and third reaction rates provides the total adsorption of HC on the HCT material, whereas the combination of the second and fourth reaction rates provides the total desorption of HC on the HCT material.

[0046] The equilibrium reaction between the acid-free sites (Z) of HCT 209 and the hydrocarbon (HC) to form the hydrocarbon-occupied sites (ZHC) can be expressed by the following relationship: Z+HC↔ZHC

[0047] Similarly, the equilibrium reaction between the acidic sites (ZH) of HCT 209 and the hydrocarbon (HC) to form the hydrocarbon-occupied sites (ZHHC) can be expressed by the following relationship: ZH+HC↔ZHHC.

[0048] According to one or more embodiments, the first reaction rate representing HC adsorption at the acid-free sites of the HCT can be expressed by Equation 1: rdes=θZHCA−1Zexp(EaZ+ΔHZ−RT), the second reaction rate, which represents the HC desorption at the acid-free sites of the HCT, can be expressed by equation 2: rads=[HC]θZHA1ZHexp(EaZH−RT), the third reaction rate, which represents the HC adsorption at the acidic sites of the HCT, can be expressed by equation 3: rads=[HC]θZHA1ZHexp(EaZH−RT), and the fourth reaction rate, which represents the HC desorption at the acidic sites of the HCT, can be expressed by equation 4: rdes=θZHHCA−1ZHexp(EaZH+ΔHZH−RT),

[0049] In equations 1 to 4, [HC] is a concentration of the hydrocarbon by the HCT in moles per liter (mol / l or parts per million, ppm); θ Z a site density of the acid-free sites (Z) of the HCT that are not bound by hydrocarbon (0 to 1); is θ ZHC a site density of the acid-free sites (ZHC) of the HCT bound by hydrocarbon (0 to 1); is θ ZH a site density of the acidic sites (ZH) of the HCT that are not bound by hydrocarbon (0 to 1); is θ ZHHC a site density of the acidic sites (ZHHC) of the HCT bound by hydrocarbon (0 to 1). The sum of θ Z and θ ZHC is 1, where the sum of θ ZH and θ ZHHC 1 is A 1Z is a pre-exponential factor of the acid-free sites (Z) of the HCT for hydrocarbon adsorption; A -1Zis a pre-exponential factor of the acid-free sites (ZHC) of the HCT for hydrocarbon desorption; A 1ZH is a pre-exponential factor of the acidic sites (ZH) of the HCT for hydrocarbon adsorption; A -1ZH is a pre-exponential factor of the acidic sites (ZHHC) of the HCT for hydrocarbon desorption; Ea z is an activation energy of an adsorption reaction at the acid-free sites (Z) of the HCT; Ea zH is an activation energy of the adsorption reaction at the acidic sites (ZH) of the HCT; ΔH Z is a hydrocarbon adsorption heat at the acid-free sites (Z) of the HCT in kilojoules per mol (kJ / mol); ΔH ZHis the heat of hydrocarbon adsorption at the acidic sites (ZH) of the HCT in kJ / mol; R is the universal gas constant; and T is the temperature in Kelvin. It can be assumed that HC adsorption is not an activated process at either the acid-free sites (Z) or the acidic sites (ZH), so the activation energy is zero. The equilibrium storage can be calculated assuming that r ads = r des for each of the acid-free sites (Z) and the acid-containing sites (ZH).

[0050] Therefore, if r ads < r des , the HCT desorbs HC. It is noted that Z and ZH are determined by the type of HCT material. According to one or more embodiments, for each type of HC, equations 1 to 4 can be used to determine parameters for ΔH Z , ΔH ZH , A 1Z , A -1Z , A 1ZH and A -1ZH to adapt.

[0051] According to some embodiments, the controller may be further configured to adjust an aftertreatment operation on the hydrocarbon released by the hydrocarbon trap based on the hydrocarbon storage level, a net reaction rate of hydrocarbon desorption from the hydrocarbon trap, or a combination thereof. The net reaction rate of hydrocarbon desorption from the hydrocarbon trap may be determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate. Adjusting the aftertreatment operation may include, for example, selectively operating the exhaust gas heating unit 213, selectively supplying an airflow at the air injection port 211, or a combination thereof. The control unit 217 may, for example,be configured to supply the airflow upstream of the HCT 209 after the HCT 209 has finished adsorbing or capturing hydrocarbons and before the HCT 209 begins to desorb or release the hydrocarbons. According to some embodiments, the control unit 217 may be configured to supply the airflow upstream of the HCT 209 while the HCT 209 is desorbing the hydrocarbons. For example, according to one or more embodiments, the control unit 217 may be configured to supply the airflow upstream of the HCT 209 after the HCT 209 has finished adsorbing the hydrocarbons and while the HCT 209 is desorbing the hydrocarbons.

[0052] According to some embodiments, the exhaust gas heating unit 213 may be selectively operated when a net reaction rate of hydrocarbon desorption from the HCT 209 is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the HCT 209 may be determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate. According to some embodiments, the air flow may be selectively supplied to the air injection port 211 when a net reaction rate of hydrocarbon desorption from the HCT 209 is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the HCT 209 may be determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.According to some embodiments, an amount of air supplied at the air injection port 211 may be proportional to a calculated oxygen deficiency at the second catalyst 215.

[0053] According to some embodiments, the control unit 217 may be operatively connected to a number of sensors to monitor the exhaust treatment system 200. The control unit may include a control module (not shown). As used herein, the term module refers to an application-specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory executing one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality. Example sensors include hydrocarbon sensors, oxygen sensors, temperature sensors, pressure sensors, or the like, or a combination thereof. The signal generated by a sensor may be transmitted to the control unit 217 and may be processed by the control unit 217, for example,for the operation or adjustment of the exhaust gas treatment system 200.

[0054] According to some embodiments, the exhaust treatment system 200 may include a first sensor 221 located upstream of the HCT 209 and downstream of the first catalyst 205. The first sensor 221 may, for example, be used to measure a concentration of one or more gases (e.g., oxygen, carbon dioxide, hydrocarbons, or the like, or a combination thereof) present in the exhaust conduit 207. The first sensor 221 may, for example, be used to measure a temperature and / or pressure present in the exhaust conduit 207. The first sensor 221 may, for example, be located immediately at the inlet of the HCT 209 to determine a concentration of the gases, a temperature, and / or a pressure at the inlet of the HCT 209.

[0055] According to some embodiments, the exhaust treatment system 200 may include a second sensor 223 located downstream of the HCT 209 and upstream of the exhaust heating unit 213. The second sensor 223 may, for example, be used to measure a concentration of one or more gases (e.g., oxygen, carbon dioxide, hydrocarbons, or the like, or a combination thereof) present in the exhaust conduit 207. The second sensor 223 may, for example, be used to measure a temperature and / or pressure present in the exhaust conduit 207. The second sensor 223 may, for example, be located immediately at the outlet of the HCT 209 to determine a concentration of the gases, a temperature, and / or a pressure at the outlet of the HCT 209.

[0056] The control unit 217 is operatively connected to the hydrocarbon storage model and is used to evaluate or determine a storage state of the HCT 209 based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate. The storage state of the HCT 209 may be evaluated, for example, based on time, temperature, and / or hydrocarbon concentration. According to some embodiments, the storage state and / or the model may be adjusted based on the measured parameters (e.g., the concentrations of the gases, temperature, and / or pressure). According to some embodiments, the storage state may be further evaluated, for example, by comparing the concentrations of the gases, temperature, and / or pressure at the inlet of the HCT 209 with the concentrations of the gases, temperature, and / or pressure at the outlet of the HCT 209.According to some embodiments, the memory state of the HCT 209 may be further evaluated based on the timing of an engine event, such as the time elapsed since a cold start of an engine, or the like.

[0057] As used herein, the term "storage state" refers to the state of the hydrocarbon trap and can be an active state, an inactive state, or a release state. The term "active state" indicates that hydrocarbons are stored (e.g., adsorbed) in the HCT 209, the term "release state" indicates that hydrocarbons are being released from the HCT 209, and the term "inactive state" indicates that the hydrocarbons in the HCT 209 are neither stored nor released. The active state can be, for example,The active state may be indicated when the concentration of hydrocarbons at the inlet of the HCT 209 is determined to be higher than a concentration of hydrocarbons at an outlet of the HCT 209, the release state may be indicated when the concentration of hydrocarbons at the outlet of the HCT 209 is determined to be higher than the concentration of hydrocarbons at the inlet of the HCT 209, and the inactive state may be indicated when the concentration of hydrocarbons at the inlet of the HCT 209 is determined to be substantially the same as the concentration of hydrocarbons at the outlet of the HCT 209. The storage phase may be determined based on the hydrocarbon storage model and / or using any number of parameters, such as gas concentrations, time, pressure, and / or temperature.

[0058] Additionally, one or more sensors may also be located in the various components of the exhaust treatment system 200. According to some embodiments, the one or more sensors may include one or more temperature sensors 225, 227, 229 in contact with the components of the exhaust treatment system 200. For example, the exhaust treatment system 200 may include a first temperature sensor 225 configured to measure the temperature of the HCT 209, a second temperature sensor 227 configured to measure the temperature of the exhaust heating unit 213, and / or a third temperature sensor 229 configured to measure the temperature of the second catalyst 215.According to some embodiments, a temperature signal generated by a temperature sensor may be transmitted to the control unit 217 and interpreted by the control unit 217 as required for operation of the exhaust treatment system 200. The temperature sensors may be in fluid communication with the exhaust gas within the respective components and / or may be a measurement of the component temperatures.

[0059] As mentioned above, the exhaust treatment system 200 may include an exhaust conduit 207, which may include multiple segments, for transporting the exhaust gas from the internal combustion engine 201 to the various exhaust treatment devices of the exhaust treatment system 200. As shown in Fig. For example, as illustrated in Figure 2, the exhaust treatment system 200 includes segments of an exhaust conduit 207 that fluidly connects the first catalyst 205, the HCT 209, the exhaust heating unit 213, and the second catalyst 215. The outlet of the second catalyst 215 may include an exhaust pipe that discharges the treated exhaust gas to the ambient atmosphere.

[0060] Another aspect provides a method for treating an exhaust gas using the exhaust treatment system 200. The method includes operating the internal combustion engine 201 to provide an exhaust fluid (e.g., an exhaust stream) at the exhaust outlet 203. The exhaust fluid is directed or transported through the exhaust treatment system 200 and through the first catalyst 205, the HCT 209, the exhaust heating unit 213, and the second catalyst 215. The exhaust treatment system 200 further includes the hydrocarbon storage model and the controller 217 operatively connected to the hydrocarbon storage model. The controller 217 is configured to perform a method for determining a hydrocarbon storage level of the HCT 209, as mentioned above, by a method including determining a first reaction rate representing a hydrocarbon adsorption rate at the acid-free sites of the HCT 209.determining a second reaction rate representing a hydrocarbon desorption rate at the non-acidic sites of the HCT 209; determining a third reaction rate representing a hydrocarbon adsorption rate at the acidic sites of the HCT 209; determining a fourth reaction rate representing a hydrocarbon desorption rate at the acidic sites of the HCT 209; and determining the hydrocarbon storage level in the HCT 209 based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate.

[0061] According to some embodiments of the method, the first reaction rate may be represented by Equation 1, the second reaction rate may be represented by Equation 2, the third reaction rate may be represented by Equation 3, and the fourth reaction rate may be represented by Equation 4, as provided herein.

[0062] According to some embodiments, the method may further include adjusting an aftertreatment operation on the hydrocarbon released by the HCT 209 based on the hydrocarbon storage level, a net reaction rate of hydrocarbon desorption from the HCT 209, or a combination thereof, wherein the net reaction rate of hydrocarbon desorption from the HCT 209 may be determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate. Adjusting the aftertreatment operation may include, for example, selectively operating the exhaust heating unit 213, selectively supplying an airflow at the air injection port 211, or a combination thereof.

[0063] According to some embodiments, the exhaust heating unit 213 may be operated when a net reaction rate of hydrocarbon desorption from the HCT 209 is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the HCT 209 is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate. According to some embodiments, the exhaust heating unit, for example, is not operated when the net reaction rate of hydrocarbon desorption from the HCT 209 is zero.

[0064] According to some embodiments, the method may include delivering the air flow to the air injection port 211 when a net reaction rate of hydrocarbon desorption from the HCT 209 is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the HCT 209 is determined based on the first reaction rate, the second reaction rate, the third reaction rate, and the fourth reaction rate. The air flow may be injected via the air injection port 211 as described herein. For example, the air flow may be combined with the exhaust gas output from the first catalyst 205 at a location proximate the outlet of the first catalyst 205. According to other embodiments, the air injection port 211 may be proximate the inlet of the HCT 209.

[0065] According to some embodiments, the method may include supplying the air stream after the HCT 209 has finished adsorbing hydrocarbons and before the HCT 209 begins to desorb hydrocarbons. According to some embodiments, the method may include supplying the air stream after the HCT 209 has finished adsorbing hydrocarbons and while the HCT 209 is desorbing the hydrocarbons. According to some aspects, the method may further include stopping supplying the air stream after the HCT 209 has finished desorbing the hydrocarbons. For example, according to some embodiments, the air stream is not supplied before the HCT 209 has reached a hydrocarbon desorption temperature. According to some embodiments, the air stream may not be supplied before the second catalyst 215 has reached a hydrocarbon oxidation temperature.According to some embodiments, the air flow may not be supplied when the net reaction rate of hydrocarbon desorption from the HCT 209 is zero.

[0066] The method may optionally include measuring a temperature, a gas concentration, a pressure, or a combination thereof using a first sensor 221 located upstream of the HCT 209 and downstream of the first catalyst 205.

[0067] According to some embodiments, the method may further include selectively delivering the airflow based on the timing of an engine event, wherein the airflow is delivered after the hydrocarbon trap stops adsorbing hydrocarbons and before the hydrocarbon trap begins desorbing the hydrocarbons. The engine event may be measured, for example, from the cold start of an engine.

[0068] According to some embodiments, the method may further include measuring a temperature, a gas concentration, a pressure, or a combination thereof using a second sensor 223 located downstream of the HCT 209 and upstream of the exhaust gas heating unit (HER) 213.

[0069] According to some embodiments, the airflow may be supplied at any suitable air mass flow rate. For example, the airflow may be supplied at an air mass flow rate sufficient to provide a suitable temperature differential between a hydrocarbon release temperature at the HCT 209 and a hydrocarbon oxidation temperature at the catalyst 215. As used herein, the term "hydrocarbon release temperature" refers to a temperature at which hydrocarbons are released (e.g., desorbed) from the HCT 209. As used herein, the term "hydrocarbon oxidation temperature" refers to a temperature at which hydrocarbons are oxidized at the catalyst 215.

[0070] According to one or more embodiments, the air flow may be supplied at an air mass flow rate of 1 to 30 liters per second (l / s). For example, the air flow may be supplied at an air mass flow rate of 2.5 to 30 l / s or 5 to 25 l / s, but the embodiments are not limited thereto. According to some embodiments, the air flow is supplied at an air mass flow rate sufficient to provide a suitable temperature difference, wherein the temperature difference is a difference between a temperature of the HCT 209 and a temperature of the second catalyst 215. According to some embodiments, the air flow is supplied at an air mass flow rate sufficient to provide a suitable temperature difference, wherein the temperature difference is a difference between a temperature of the HCT 209 and a temperature of the exhaust gas heating unit 213.According to some embodiments, a method for selecting the HCT material and selecting the catalyst material to maximize the temperature difference is provided.

[0071] According to some embodiments, the air stream may be supplied at an air mass flow rate sufficient to provide a temperature difference of at least 10°C, at least 25°C, at least 50°C, at least 100°C, at least 150°C, at least 180°C, or at least 200°C, wherein the temperature difference is a difference between a temperature of the HCT 209 and a temperature of the second catalyst 215. According to some embodiments, the air stream may be supplied at an air mass flow rate sufficient to provide a temperature difference of at least 10°C, at least 25°C, at least 50°C, at least 100°C, at least 150°C, at least 180°C, or at least 200°C, wherein the temperature difference is a difference between a temperature of the HCT 209 and a temperature of the exhaust gas heating unit 213.

[0072] Fig. 3 depicts a flowchart 300 illustrating a method for treating exhaust gas from an internal combustion engine, according to one or more embodiments. The flowchart begins at block 301, where it is determined whether the hydrocarbon trap has reached the hydrocarbon release temperature. If the hydrocarbon trap has not reached the release temperature, then flow proceeds to block 302 with air injection remaining off. If the hydrocarbon trap has reached the release temperature, then flow proceeds to block 303, where it is determined whether the second catalyst has reached the oxidation temperature. If the second catalyst has not reached the oxidation temperature, then flow proceeds to block 304 with air injection remaining off. If the second catalyst has reached the oxidation temperature, then flow proceeds to block 305, where it is determined whether the exhaust pipe EQR is greater than 1.If the exhaust pipe EQR is not greater than 1, then flow proceeds to block 306, where air injection remains off. If the exhaust pipe EQR is greater than 1, then flow proceeds to block 307, where it is determined whether the hydrocarbon release rate from the hydrocarbon trap is zero. If the hydrocarbon release rate from the hydrocarbon trap is zero, then flow proceeds to block 309, where air injection remains off. If the hydrocarbon release rate from the hydrocarbon trap is not zero, then flow proceeds to block 308, where air injection is turned on.

[0073] The term "EQR" refers to the equivalence ratio used to describe the air-fuel ratio in gasoline engines and aftertreatment systems. An EQR of 1 means that combustion occurs under stoichiometric conditions, where there is just enough air to burn all of the fuel. An EQR > 1 means that there is more air than needed for stoichiometric combustion, which is also referred to as lean (or fuel-lean) conditions. An EQR < 1 means that there is less air than needed for stoichiometric combustion, which is also referred to as rich (or fuel-rich) conditions.

[0074] Fig. 4 depicts a flowchart 400 illustrating a method for treating exhaust gas from an internal combustion engine according to one or more embodiments. The flowchart begins at block 401, where it is determined whether the hydrocarbon release rate from the hydrocarbon trap is zero. If the hydrocarbon release rate from the hydrocarbon trap is zero, then flow proceeds to block 403, where the electric heater is off. If the hydrocarbon release rate from the hydrocarbon trap is not zero, flow proceeds to block 402, where the electric heater is turned on.

[0075] In Fig. Figure 5A illustrates a graph of the hydrocarbon concentration C1 (parts per million, ppm) measured at the inlet of the HCT unit (501), measured at the outlet of the HCT unit (502), and calculated using equations 1 through 4 based on the time from cold start of the engine and the temperature (503). The data were collected using a laboratory reactor model. The graph in Fig. Figure 5A also shows the temperature at the HCT inlet (504) and the temperature at the second catalyst (505). Between about 300 seconds and about 450 seconds, there was a first release of hydrocarbons from the HCT unit, followed by a second release of hydrocarbons from the HCT unit, which was observed between about 475 seconds and about 700 seconds. Fig. Figure 5B illustrates a graph of the surface coverage (0 to 1) of the HCT material for each of the acid-free sites occupied by hydrocarbon (510) and the acidic sites occupied by hydrocarbon (511) based on time and temperature. The graph in Fig. 5B also shows the temperature at the HCT inlet (504) and the temperature at the second catalyst (505). The time axis in Fig. 5B corresponds to the time axis in Fig. 5A and shows that the first release of hydrocarbons from the HCT unit corresponds to the release of hydrocarbons from the acid-free sites, whereas the second release of hydrocarbons from the HCT unit corresponds to the release of hydrocarbons from the acidic sites. For the evaluation using equations 1 to 4, the site density of the sites for Z was 2.5 mol / m 3 and for ZH 1.2 mol / m 3 ; the heat of adsorption DH wasz 50.7 kJ / mol and was DH ZH 67.2 kJ / mol; and the pre-exponential factors A 1Z 6,983 10 5 ; A -1Z 9.85 10 11 ; A 1ZH 9.78 10 2 ; and A -1ZH 4,925 10 3 .

[0076] The technical methods described herein promote improvements to emission control systems used in internal combustion engines, such as those used in vehicles. The technical features described herein improve the conventional emission control system by providing a control scheme based on the capture and release of hydrocarbons by the hydrocarbon trap. The control scheme advantageously reduces emissions during cold starts.

[0077] In terms of hardware architecture, the emissions control system may be implemented in part using a computing device, which may include a processor, memory, and one or more input and / or output device (I / O) interfaces communicatively coupled via a local interface. The local interface may include, for example, but is not limited to, one or more buses and / or other wired or wireless connections. The local interface may include additional elements, omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers, to enable communications. Further, the local interface may include address, control, and / or data connections to enable appropriate communication between the aforementioned components.

[0078] When the computing device is in operation, the processor may be configured to execute software stored within the memory, transfer data to and from the memory, and generally control the operations of the computing device according to the software. The software in the memory is read in whole or in part by the processor, perhaps buffered within the processor, and then executed. The processor may be a hardware device for executing software, particularly the software stored in the memory. The processor may be a custom-built or off-the-shelf processor, a central processing unit (CPU), an auxiliary processor among several processors associated with the computing device, a semiconductor-based microprocessor (in the form of a microchip or chipset), or generally any device for executing software.

[0079] The memory may include any one or a combination of volatile storage elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, VRAM, etc.)) and / or non-volatile storage elements (e.g., ROM, hard disk, CD-ROM, etc.). Furthermore, the memory may include electronic, magnetic, optical, and / or other types of storage media. It is noted that the memory may also have a distributed architecture in which various components are located remotely from one another but are accessible by the processor.

[0080] The software in memory may contain one or more separate programs, each containing an ordered collection of executable instructions for implementing logical functions. A system component embodied as software may also be interpreted as a source program, an executable program (object code), a script, or any other entity comprising a set of instructions to be executed. When the program is created as a source program, it is compiled via a compiler, assembler, interpreter, or the like, which may or may not be contained within memory.

[0081] It should be mentioned that Fig.3 shows an architecture, functionality, and / or operating scheme that may be partially implemented using software. In this regard, one or more of the blocks may be interpreted as representing a module, segment, or section of code comprising one or more executable instructions for implementing the one or more specified logical functions. It should also be noted that in some alternative implementations, the functions specified in the blocks may occur out of order and / or not at all. For example, two blocks shown one after the other may actually execute substantially concurrently, or the blocks may sometimes execute in the reverse order depending on the functionality involved.

[0082] It should be noted that any of the functionality described herein may be embodied in any computer-readable medium for use by or in connection with an instruction execution system, an instruction execution device, or an instruction execution apparatus, such as a computer-based system, a system including processors, or any other system that can retrieve the instructions from the instruction execution system, the instruction execution device, or the instruction execution apparatus and execute the instructions. In the context of this document, a "computer-readable medium" contains, stores, communicates, distributes, and / or transports the program for use by or in connection with the instruction execution system, the instruction execution device, or the instruction execution apparatus. The computer-readable medium may, for example,an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or apparatus. More specific examples (a non-exhaustive list) of a computer-readable medium include a portable computer diskette (magnetic), random access memory (RAM) (electronic), read-only memory (ROM) (electronic), erasable programmable read-only memory (EPROM or flash memory) (electronic), and portable compact disk read-only memory (CD-ROM) (optical).

[0083] The terms "a" and "an" do not imply a limitation of quantity, but rather denote the presence of at least one of the designated elements. The term "or" means "and / or" unless the context clearly indicates otherwise. Reference throughout the specification to "an aspect" means that a particular element (e.g., a feature, structure, step, or property) described in connection with the aspect is included in at least one aspect described herein and may or may not be present in other aspects. In addition, it should be recognized that the described elements in the various aspects may be combined in any suitable manner.

[0084] When an element, such as a layer, film, region, or substrate, is described as being "on" another element, it may be directly on top of the other element, or there may also be intervening elements. Conversely, when an element is described as being "directly on" another element, there are no intervening elements.

[0085] Unless otherwise specified herein, all testing standards are the most recent standard in effect as of the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the testing standard appears. Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs.

Claims

[1] Exhaust gas treatment system (200), comprising: a first catalyst (205) downstream of an exhaust outlet (203) of an internal combustion engine (201), wherein the first catalyst (205) receives exhaust gas emitted from the exhaust outlet (203); a hydrocarbon trap (209) downstream of the first catalyst (205), wherein the hydrocarbon trap (209) receives exhaust gas emitted from the first catalyst (205); an air injection port (211) configured to supply an airflow upstream of the hydrocarbon trap (209) and downstream of the first catalyst (205); an exhaust gas heating unit (213) downstream of the hydrocarbon trap (209), wherein the exhaust gas heating unit (213) receives exhaust gas emitted by the hydrocarbon trap (209); a second catalyst (215) downstream of the exhaust gas heating unit (213), wherein the second catalyst (215) receives exhaust gas emitted by the exhaust gas heating unit (213); a hydrocarbon storage model; and a controller (217) operationally connected to the hydrocarbon storage model, wherein the controller (217) is configured to execute a method for determining a hydrocarbon storage level of the hydrocarbon trap (209), the method comprising: Determining a first reaction rate that represents a hydrocarbon adsorption rate at acid-free sites of the hydrocarbon trap (209); Determining a second reaction rate representing a hydrocarbon desorption rate at acid-free sites of the hydrocarbon trap (209); Determining a third reaction rate representing a hydrocarbon adsorption rate at acidic sites of the hydrocarbon trap (209); Determining a fourth reaction rate representing a hydrocarbon desorption rate at acidic sites of the hydrocarbon trap (209); and Determining the hydrocarbon storage level in the hydrocarbon trap (209) based on the first reaction rate, the second reaction rate, the third reaction rate and the fourth reaction rate. [2] Exhaust gas treatment system (200) according to claim 1, wherein the controller (217) is further configured to set a post-treatment operation on the hydrocarbon released by the hydrocarbon trap (209) based on the hydrocarbon storage level, a net reaction rate of hydrocarbon desorption from the hydrocarbon trap (209) or a combination thereof, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap (209) is determined based on the first reaction rate, the second reaction rate, the third reaction rate and the fourth reaction rate. [3] Exhaust gas treatment system (200) according to claim 1, wherein the first reaction rate is represented by equation 1: rads=[HC]θZA1Zexp(EaZ−RT), The second reaction rate is represented by equation 2: rdes=θZHCA−1exp(EaZ+ΔHZ−RT), The third reaction rate is represented by equation 3: rads=[HC]θZHA1ZHexp(EaZH−RT), The fourth reaction rate is represented by equation 4: rdes=θZHHCA−1ZHexp(EaZH+ΔHZH−RT), where in equations 1 to 4 [HC] is a concentration of the hydrocarbon through the hydrocarbon trap (209), θ Z a site density of the acid-free sites of the hydrocarbon trap (209) that are not bound by hydrocarbons, θ ZHC a site density of the acid-free sites of the hydrocarbon trap (209) that are bound by hydrocarbons, θ ZH a site density of the acidic sites of the hydrocarbon trap (209) that are not bound by hydrocarbons, θ ZHHCa site density of the acidic sites of the hydrocarbon trap (209) which are bound by hydrocarbons, A 1Z a pre-exponential factor of the acid-free sites of the hydrocarbon trap (209) for hydrocarbon adsorption is, A -1Z a pre-exponential factor of the acid-free sites of the hydrocarbon trap (209) for hydrocarbon desorption is, A 1ZH a pre-exponential factor of the acidic sites of the hydrocarbon trap (209) for hydrocarbon adsorption is, A -1ZH a pre-exponential factor of the acidic sites of the hydrocarbon trap (209) for hydrocarbon desorption is, Ea z an activation energy of an adsorption reaction at the acid-free sites of the hydrocarbon trap (209) is, Ea zHan activation energy of the adsorption reaction at the acidic sites of the hydrocarbon trap (209) is, ΔH Z a hydrocarbon adsorption heat at the acid-free sites of the hydrocarbon trap (209) is, ΔH ZH a hydrocarbon adsorption heat at the acidic sites of the hydrocarbon trap (209) is, R is the universal gas constant and T is the temperature. [4] Exhaust gas treatment system (200) according to claim 1, wherein the exhaust gas heating unit (213) is operated selectively when a net reaction rate of hydrocarbon desorption from the hydrocarbon trap (209) is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap (209) is determined based on the first reaction rate, the second reaction rate, the third reaction rate and the fourth reaction rate. [5] Exhaust gas treatment system (200) according to claim 1, wherein the airflow is selectively supplied at the air injection opening (211) when a net reaction rate of hydrocarbon desorption from the hydrocarbon trap (209) is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap (209) is determined based on the first reaction rate, the second reaction rate, the third reaction rate and the fourth reaction rate. [6] Method for treating exhaust gases from an internal combustion engine (201) in a motor vehicle (10), the method comprising: Operating the internal combustion engine (201) to provide an exhaust fluid at an exhaust outlet (203) of the internal combustion engine (201); Guiding the exhaust fluid through an exhaust treatment system (200), which includes: a first catalyst (205) downstream of the exhaust outlet (203) of the internal combustion engine (201), wherein the first catalyst (205) receives exhaust gas emitted from the exhaust outlet (203); a hydrocarbon trap (209) downstream of the first catalyst (205), wherein the hydrocarbon trap (209) receives exhaust gas emitted by the first catalyst (205); an air injection port (211) configured to supply an airflow upstream of the hydrocarbon trap (209) and downstream of the first catalyst (205); an exhaust gas heating unit (213) downstream of the hydrocarbon trap (209), wherein the exhaust gas heating unit (213) receives exhaust gas emitted by the hydrocarbon trap (209); a second catalyst (215) downstream of the exhaust gas heating unit (213), wherein the second catalyst (215) receives exhaust gas emitted by the exhaust gas heating unit (213); a hydrocarbon storage model; and a controller (217) which is operationally connected to the hydrocarbon storage model, wherein the controller (217) is configured to execute a method for determining a hydrocarbon storage level of the hydrocarbon trap (209); Determining a first reaction rate that represents a hydrocarbon adsorption rate at acid-free sites of the hydrocarbon trap (209); Determining a second reaction rate representing a hydrocarbon desorption rate at acid-free sites of the hydrocarbon trap (209); Determining a third reaction rate representing a hydrocarbon adsorption rate at acidic sites of the hydrocarbon trap (209); Determining a fourth reaction rate representing a hydrocarbon desorption rate at acidic sites of the hydrocarbon trap (209); and Determining the hydrocarbon storage level in the hydrocarbon trap (209) based on the first reaction rate, the second reaction rate, the third reaction rate and the fourth reaction rate. [7] Method according to claim 6, wherein the first reaction rate is represented by equation 1: rads=[HC]θZA1Zexp(EaZ−RT), The second reaction rate is represented by equation 2: rdes=θZHCA−1Zexp(EaZ+ΔHZ−RT), The third reaction rate is represented by equation 3: rads=[HC]θZHA1ZHexp(EaZH−RT), The fourth reaction rate is represented by equation 4: rdes=θZHHCA−1ZHexp(EaZH+ΔHZH−RT), where in equations 1 to 4 [HC] is a concentration of hydrocarbon through the hydrocarbon trap (209), θ Z a site density of the acid-free sites of the hydrocarbon trap (209) that are not bound by hydrocarbons, θ ZHC a site density of the acid-free sites of the hydrocarbon trap (209) that are bound by hydrocarbons, θ ZH a site density of the acidic sites of the hydrocarbon trap (209) that are not bound by hydrocarbons, θ ZHHC a density of acidic sites in the hydrocarbon trap that are bound by hydrocarbons, A 1Z a pre-exponential factor of the acid-free sites of the hydrocarbon trap (209) for hydrocarbon adsorption is, A -1Za pre-exponential factor of the acid-free sites of the hydrocarbon trap (209) for hydrocarbon desorption is, A 1ZH a pre-exponential factor of the acidic sites of the hydrocarbon trap (209) for hydrocarbon adsorption is, A -1ZH a pre-exponential factor of the acidic sites of the hydrocarbon trap (209) for hydrocarbon desorption is, Ea z an activation energy of an adsorption reaction at the acid-free sites of the hydrocarbon trap (209) is, Ea zH an activation energy of the adsorption reaction at the acidic sites of the hydrocarbon trap (209) is, ΔH Z a hydrocarbon adsorption heat at the acid-free sites of the hydrocarbon trap (209) is, ΔH ZH a hydrocarbon adsorption heat at the acidic sites of the hydrocarbon trap (209) is, R is the universal gas constant and T is the temperature. [8] The method of claim 6, further comprising operating the exhaust gas heating unit (213) when the net reaction rate of hydrocarbon desorption from the hydrocarbon trap (209) is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap (209) is determined based on the first reaction rate, the second reaction rate, the third reaction rate and the fourth reaction rate. [9] The method of claim 6, further comprising supplying the airflow to the air injection opening (211) when the net reaction rate of hydrocarbon desorption from the hydrocarbon trap (209) is greater than zero, wherein the net reaction rate of hydrocarbon desorption from the hydrocarbon trap (209) is determined based on the first reaction rate, the second reaction rate, the third reaction rate and the fourth reaction rate. [10] Method according to claim 6, wherein the airflow is not supplied before the hydrocarbon trap (209) has reached a hydrocarbon desorption temperature.

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