A process for producing renewable aviation fuel by medium- and low-pressure hydrogenation

Abstract

The present invention is applicable to the field of aviation fuel technology, and provides a process for producing renewable aviation fuel by medium and low pressure hydrogenation, comprising the following steps: mixing a liquid catalyst containing molybdenum with a liquid biomass raw material, and then feeding it into a pre-hydrogenation reactor under pre-hydrogenation conditions to obtain a liquid intermediate product; the liquid intermediate product is separated by gas-liquid separation and then separated by post-treatment to obtain a primary hydrogenation product; the primary hydrogenation product enters a supplementary hydrogenation and upgrading reactor containing a sulfided catalyst to obtain an upgraded intermediate product; the upgraded intermediate product enters a hydrogenation stripping tower to separate a gas product to obtain a secondary hydrogenation and upgrading product; the secondary hydrogenation and upgrading product enters a hydroisomerization reactor, reacts in the presence of a reduced catalyst and under specific hydroisomerization cracking reaction conditions, and then undergoes product fractionation to obtain a renewable aviation fuel. The present invention has the advantages of strong raw material adaptability, low catalyst usage, high processing efficiency, etc., and reduces operating costs.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation fuel, and in particular relates to a process for producing renewable aviation fuel by medium- and low-pressure hydrogenation. Background Art

[0002] With increasingly stringent environmental regulations and the increasing demand for transportation fuels, including aviation fuel, people are beginning to seek renewable resources to replace traditional fossil fuel resources. Among them, a wide variety of animal and plant oils (such as soybean oil, palm oil, corn oil, rapeseed oil, microalgae oil, lard, tallow and waste cooking oil, etc.) are regarded as ideal substitutes for petroleum resources. These oils all contain similar chemical components, including monoglycerides, diglycerides, triglycerides and a small amount of free fatty acids, among which triglycerides contain the most. Although the fatty acid chain length of the triglycerides contained is between 8 and 24, due to their own high viscosity and oxygen content, these raw materials cannot be used directly as fuel oil and need to be processed into fuel oil that meets the performance standards of traditional petroleum-based fuels.

[0003] Triglycerides, free fatty acids and fatty acid methyl esters can be catalytically converted into biofuels using traditional hydrodesulfurization catalysts, but the resulting products are mainly straight-chain alkanes, which belong to diesel components and are difficult to meet the standards of aviation fuel oil. In order to increase the content of aviation fuel oil components in the product, selective hydrocracking and isomerization processes must be added after the hydrotreatment operation. The former can shorten the carbon chain length to increase the yield of aviation fuel oil components, and the latter can convert straight-chain alkanes into straight-chain alkanes to improve the low-temperature performance of the product. The prior art converts vegetable oil into an intermediate base distillate oil through two processes of hydrodeoxygenation and isomerization. Among them, a hydrodesulfurization catalyst and a metal-containing molecular sieve are used as catalysts for hydrodeoxygenation and isomerization, respectively. In addition, the prior art uses an isomerization process to process biomass as a raw material and obtain an alkane product through hydrodeoxygenation. As mentioned above, the alkanes of aviation fuel components can be produced through a continuous process of hydrodeoxygenation-hydrocracking-isomerization, but the process requires multiple fixed bed reactors in series, and the catalyst used is also a traditional supported hydrogenation catalyst. my country currently produces millions of tons of waste oils and fats every year, such as waste cooking oils and fats, sewage oils, acidified oils, etc., which have high colloid and metal content and high acid value, and are very likely to cause coking and poisoning of supported catalysts, causing their activity to drop rapidly. Therefore, existing oil hydrogenation companies will pre-treat the raw materials to remove impurities such as ash, pigments and colloids before use to eliminate their effects on the catalyst. This process is complicated and costly, and will produce a large amount of hazardous waste after large-scale production. For this reason, we propose a process for producing renewable aviation fuel by medium and low pressure hydrogenation. Summary of the invention

[0004] The object of the present invention is to provide a process for producing renewable aviation fuel by medium- and low-pressure hydrogenation, aiming to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A process for producing renewable aviation fuel by medium- and low-pressure hydrogenation comprises the following steps:

[0007] Step S1: mixing a liquid catalyst containing molybdenum with a pressurized, heated and melted liquid biomass feedstock, and then feeding the mixture into a pre-hydrogenation reactor under pre-hydrogenation conditions to obtain a liquid intermediate product;

[0008] Step S2: After the liquid intermediate product is subjected to gas-liquid separation, it is separated by non-hydrogenation post-treatment to obtain a primary hydrogenation product;

[0009] Step S3: the primary hydrogenation product enters a supplementary hydrogenation upgrading reactor containing a sulfided catalyst to obtain an upgraded intermediate product;

[0010] Step S4: the upgraded intermediate product enters a hydrogen stripping tower to separate the gas product to obtain a secondary hydrogenation upgraded product;

[0011] Step S5: The secondary hydrogenation upgrading product enters the hydroisomerization reactor, reacts in the presence of a reduced catalyst and under specific hydroisomerization cracking reaction conditions, and then undergoes product fractionation to obtain renewable aviation fuel.

[0012] Furthermore, the pre-hydrogenation conditions include: hydrogen pressure of 1-10 MPa and reaction temperature of 250-400°C.

[0013] Furthermore, the hydroisomerization cracking reaction conditions include: hydrogen pressure of 1-10 MPa and reaction temperature of 200-350°C.

[0014] Furthermore, the sulfided catalyst is a supported catalyst containing molybdenum and / or tungsten and nickel and / or cobalt metal.

[0015] Furthermore, the sulfided catalyst is a supported catalyst containing platinum or nickel metal.

[0016] Furthermore, the liquid catalyst is a liquid containing Group VIB and / or Group VIII complex metals, and the liquid catalyst is mixed into the raw material under pressure, and the added amount is 200-4000 ppm.

[0017] Furthermore, the biomass raw material is biological fat including plant fat and / or animal fat, and the biological fat is one or a mixture of fatty acid and / or fatty acid glyceride.

[0018] Furthermore, the post-processing separation includes vacuum fractionation separation and / or centrifugal separation.

[0019] Furthermore, the renewable aviation fuel is a hydrocarbon mixture derived from biomass with a density of less than 0.78 mL / g and a freezing point of less than -40°C.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] Compared with the existing renewable aviation fuel production technology that all adopts fixed bed process, the process method of producing renewable aviation fuel by medium and low pressure hydrogenation is a homogeneous pre-hydrogenation process developed for waste oil resources that are difficult to process, and has the advantages of strong raw material adaptability, small amount of catalyst and high processing efficiency; the oil raw material can be directly used after simple treatment of dehydration and removal of mechanical impurities, which reduces the operating cost; the liquid catalyst used can form highly active transition metal sulfide nanoparticles through in-situ sulfurization at the initial stage of the reaction, and compared with conventional supported solid catalysts, the utilization rate of active components is higher and the tolerance to impurities is stronger. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a process flow chart of the present invention. Implementation

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0025] An embodiment of the present invention provides a process for producing renewable aviation fuel by medium- and low-pressure hydrogenation, comprising the following steps:

[0026] Step S1: mixing a liquid catalyst containing molybdenum with a pressurized, heated and melted liquid biomass feedstock, and then feeding the mixture into a pre-hydrogenation reactor under pre-hydrogenation conditions to obtain a liquid intermediate product;

[0027] Step S2: After the liquid intermediate product is subjected to gas-liquid separation, it is separated by non-hydrogenation post-treatment to obtain a primary hydrogenation product;

[0028] Step S3: the primary hydrogenation product enters a supplementary hydrogenation upgrading reactor containing a sulfided catalyst to obtain an upgraded intermediate product;

[0029] Step S4: the upgraded intermediate product enters a hydrogen stripping tower to separate gaseous products such as circulating hydrogen to obtain a secondary hydrogenation upgraded product;

[0030] Step S5: The secondary hydrogenation upgrading product enters the hydroisomerization reactor, reacts in the presence of a reduced catalyst and under specific hydroisomerization cracking reaction conditions, and then undergoes product fractionation to obtain renewable aviation fuel.

[0031] As a preferred embodiment of the present invention, the pre-hydrogenation conditions include: a hydrogen pressure of 1-10 MPa and a reaction temperature of 250-400°C.

[0032] As a preferred embodiment of the present invention, the hydroisomerization cracking reaction conditions include: hydrogen pressure of 1-10 MPa and reaction temperature of 200-350°C.

[0033] As a preferred embodiment of the present invention, the sulfided catalyst is a supported catalyst containing molybdenum and / or tungsten and nickel and / or cobalt metal.

[0034] As a preferred embodiment of the present invention, the sulfided catalyst is a supported catalyst containing platinum or nickel metal.

[0035] As a preferred embodiment of the present invention, the liquid catalyst is a liquid containing Group VIB and / or Group VIII complex metals, and the liquid catalyst is mixed into the raw material under pressure, and the added amount is 200-4000 ppm.

[0036] As a preferred embodiment of the present invention, the biomass raw material is biological fat including plant fat and / or animal fat, and the biological fat is one or a mixture of fatty acid and / or fatty acid glyceride.

[0037] As a preferred embodiment of the present invention, the post-treatment separation includes vacuum fractionation separation and / or centrifugal separation.

[0038] As a preferred embodiment of the present invention, the renewable aviation fuel is a hydrocarbon mixture derived from biomass with a density of less than 0.78 mL / g and a freezing point of less than -40°C. Example

[0039] The slop oil provided by the enterprise was used as the raw material, and the pre-hydrogenation process of the raw material was carried out in a slurry bed reactor. The liquid catalyst addition amount was 2000 ppm, the reaction temperature was controlled at 300~380℃, the hydrogen pressure was 8MPa, and the mass hourly space velocity (WHSV) was 1.0h -1 , the volume ratio of hydrogen to oil is 800:1.

[0040] As shown in Table 1, when the temperature is 360°C or higher, the conversion rate of the raw materials is above 99%, and the liquid products are mainly fatty alcohols, fatty aldehydes and alkanes, among which the saturated alkanes are mainly C15-C18 chain alkanes. The gas phase products mainly include carbon monoxide, carbon dioxide, water and methane.

[0041] Table 1

[0042] Example

[0043] The product obtained at 360°C in Example 1 was separated and used as the primary hydrogenation product, and a supplementary hydrogenation process was carried out in a high-pressure fixed bed reactor to remove the remaining oxygen atoms. The catalyst was a conventional supported transition metal sulfide-type hydrogenation refining catalyst, the reaction temperature was controlled at 300-340°C, the hydrogen pressure was 4MPa, and the mass hourly space velocity (WHSV) was 1.5h -1 , the volume ratio of hydrogen to oil is 600:1.

[0044] As shown in Table 2, when the temperature is 300°C or higher, the deoxygenation rate of the primary hydrogenation product is above 99%, the saturated alkanes in the liquid phase product are mainly C15-C18 chain alkanes, and other by-products are light cracking products and a very small amount of aromatics. The gas phase products mainly include carbon monoxide, carbon dioxide, water and methane.

[0045] Table 2

[0046] Example

[0047] The product obtained at 320°C in Example 2 was separated and used as the secondary hydrogenation product, and a hydrocracking isomerization process was carried out in a high-pressure fixed bed reactor to increase the yield of the jet fuel fraction and reduce the freezing point of the product. The catalyst was a non-sulfurized transition metal hydroisomerization catalyst containing a molecular sieve, the reaction temperature was controlled at 280-320°C, the hydrogen pressure was 4MPa, and the mass hourly space velocity (WHSV) was 2.0h -1 , the volume ratio of hydrogen to oil is 500:1.

[0048] As shown in Table 3, when the temperature is 320℃, the isomerization rate of the secondary hydrogenation product is above 70%, the saturated alkanes in the liquid phase product are mainly C8-C16 jet fuel fractions, and other by-products are light cracking products and very small amounts of aromatics. The gas phase products mainly include alkanes below C4.

[0049] Table 3

[0050]

[0051] The above are only preferred embodiments of the present invention. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These should also be regarded as the protection scope of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A process for producing renewable aviation fuel by medium and low pressure hydrogenation, It is characterized in that The following steps are involved: Step S1: mixing a liquid catalyst containing molybdenum with a pressurized, heated and melted liquid biomass feedstock, and then feeding the mixture into a pre-hydrogenation reactor under pre-hydrogenation conditions to obtain a liquid intermediate product; Step S2: After the liquid intermediate product is subjected to gas-liquid separation, it is separated by non-hydrogenation post-treatment to obtain a primary hydrogenation product; Step S3: the primary hydrogenation product enters a supplementary hydrogenation upgrading reactor containing a sulfided catalyst to obtain an upgraded intermediate product; Step S4: the upgraded intermediate product enters a hydrogen stripping tower to separate the gas product to obtain a secondary hydrogenation upgraded product; Step S5: the secondary hydrogenation upgrading product enters a hydroisomerization reactor, reacts in the presence of a reduced catalyst and under specific hydroisomerization cracking reaction conditions, and then undergoes product fractionation to obtain renewable aviation fuel; The pre-hydrogenation conditions include: hydrogen pressure of 1-10 MPa, reaction temperature of 250-400°C; The hydroisomerization cracking reaction conditions include: hydrogen pressure of 1-10 MPa, reaction temperature of 200-350°C; The liquid catalyst is a liquid containing group VIB and / or group VIII complex metals. The liquid catalyst is mixed into the raw material under pressure, and the added amount is 200-4000 ppm.

2. The process for producing renewable aviation fuel by medium and low pressure hydrogenation according to claim 1, It is characterized in that The sulfided catalyst is a supported catalyst containing molybdenum and / or tungsten and nickel and / or cobalt metals.

3. The process for producing renewable aviation fuel by medium and low pressure hydrogenation according to claim 1, It is characterized in that The sulfided catalyst is a supported catalyst containing platinum or nickel metal.

4. The process for producing renewable aviation fuel by medium and low pressure hydrogenation according to claim 1, It is characterized in that The biomass raw material is biological oil including plant oil and / or animal fat, and the biological oil is one or a mixture of fatty acid and / or fatty acid glyceride.

5. The process for producing renewable aviation fuel by medium and low pressure hydrogenation according to claim 1, It is characterized in that The post-treatment separation includes vacuum fractionation separation and / or centrifugal separation.

6. The process for producing renewable aviation fuel by medium- and low-pressure hydrogenation according to any one of claims 1 to 5, It is characterized in that The renewable aviation fuel is a hydrocarbon mixture derived from biomass with a density of less than 0.78 mL / g and a freezing point of less than -40°C.

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