Ammonolysis Module for Diesel Exhaust Hydrogen Generation
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Solution Overview
Problem
Diesel engines emit high levels of nitrogen oxides and particulates, which are difficult to convert into harmless materials, and existing technologies face challenges in efficiently reducing these emissions while maintaining high fuel economy and torque.
Innovation Solution
The introduction of hydrogen gas generated in an ammonolysis module into diesel oxidation catalyst (DOC), catalyzed diesel particulate filter (DPF), and selective catalytic reduction (SCR) or lean NOx trap (LNT) modules improves the efficiency of nitrogen oxide reduction, lowers recycling temperatures, and reduces the need for precious metals, by hydrolyzing ammonia from urea and using it as a reducing agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen gas is injected at the front end of DOC, then DOC performance is improved and LOT is decreased, but system complexity increases due to additional hydrogen generation equipment
Solution Approach 1:
The patent combines the hydrogen generation function (ammonolysis module) with the existing exhaust gas treatment system by integrating it into the exhaust flow path. The ammonolysis module uses ammonia from urea hydrolysis to generate hydrogen in-situ, which is then fed to the DOC, merging multiple functions (urea storage, hydrolysis, ammonolysis, hydrogen generation) into a unified system that reduces overall complexity.
Solution Approach 2:
The system uses the urea already stored in the SCR module for dual purposes: first for NOx reduction via ammonia, and second for hydrogen generation via ammonolysis. This self-service approach eliminates the need for separate hydrogen storage or external hydrogen sources, as the system generates its own hydrogen from its existing chemical inventory.
2Productivity
If precious metals are loaded on DPF to oxidize nitrogen oxides to NO2, then particulate oxidation efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The patent introduces hydrogen as an intermediary substance that facilitates particulate oxidation without requiring precious metals. Hydrogen sprayed at the front end of the DPF acts as a mediator that enables low-temperature oxidation of carbon particulates, replacing the need for Pt/Pd catalysts and reducing dependency on scarce and expensive precious metal resources.
3Productivity
If hydrogen is injected at the front end of DPF, then particulate combustion temperature is lowered and recycling efficiency is improved, but energy consumption increases for hydrogen production
Solution Approach 1:
The patent changes the chemical parameters by introducing hydrogen gas to alter the combustion chemistry in the DPF. Hydrogen lowers the activation energy required for particulate oxidation, enabling combustion at reduced temperatures (200°C or less instead of 550°C). This parameter change in combustion temperature achieves efficient particulate recycling while the hydrogen is generated from exothermic ammonolysis reactions that produce heat.
4Object-generated harmful factors
If urea-SCR module is used to reduce nitrogen oxides, then NOx emission is decreased, but system complexity increases due to urea storage and hydrolysis equipment
Solution Approach 1:
The patent makes the urea-SCR module multi-functional by adding the ammonolysis capability to the existing hydrolysis catalyst. The same urea storage container and catalyst system now serve dual purposes: generating ammonia for NOx reduction and generating hydrogen for DOC enhancement and DPF regeneration. This universality eliminates the need for separate hydrogen generation equipment, reducing overall system complexity while maintaining NOx reduction effectiveness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively decreases the light-off temperature of DOC, enhances desulfuration efficiency, and improves the overall efficiency of nitrogen oxide reduction in HC-SCR and LNT modules, allowing for more effective particulate oxidation and recycling without significant changes to existing systems.
Implementation Method 1
hydrogen gas generated in an ammonolysis module... by hydrolyzing ammonia from urea
Implementation Method 2
oxidize nitrogen oxides to NO2 in exhaust gas discharged from a diesel engine
Implementation Method 3
catalysts are provided for the filter in order to decrease a temperature of combustion
Implementation Method 4
reducing nitrogen oxides (NO, NO2) by applying the ammonia as a reducing agent
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(c)
AI summary
The present invention relates to a device for discharging exhaust gas from a diesel engine by using hydrogen gas, which includes an ammonolysis module. More specifically, the present invention relates to a device for purifying exhaust gas of a diesel engine, wherein the device for discharging exhaust gas from a diesel engine comprises a DOC-DPF-LNT module formed in the downstream of diesel engine in a serial mode, further includes an ammonolysis module; the device for discharging exhaust gas from a diesel engine comprises a DOC-DPF-HC-SCR module formed in the downstream of diesel engine in a serial mode, further includes an ammonolysis module; and the device comprises an LNT-DPF module and an ammonolysis module.