CN-122010713-A - Low-carbon preparation method of bio-based acetic acid

CN122010713ACN 122010713 ACN122010713 ACN 122010713ACN-122010713-A

Abstract

The invention discloses a low-carbon preparation method of bio-based acetic acid, and relates to the technical field of biomass energy chemical industry. The method comprises the steps of adding non-grain biomass into a pyrolysis unit for pyrolysis carbonization to obtain biochar and bio-combustible gas, adding the biochar into a gasification unit for gasification to obtain synthesis gas, adding the synthesis gas into a separation unit to obtain carbon monoxide flow and reaction gas, adding the reaction gas into a synthesis unit for synthesis, adding the synthesis gas into a rectification unit for rectification and purification to obtain refined methanol, adding the refined methanol into a dehydration unit for dehydration to obtain dimethyl ether, adding the carbon monoxide flow and the dimethyl ether into a carbonyl insertion unit for carbonyl insertion to obtain methyl acetate, adding the methyl acetate into a hydrolysis unit for hydrolysis to obtain mixed liquor, and adding the mixed liquor into a purification unit for separation and purification to obtain refined acetic acid. The method for preparing acetic acid provided by the invention has the advantages of low-carbon and environment-friendly process, high raw material utilization rate and suitability for large-scale industrial production.

Inventors

LI SHIZHONG
ZHANG HUIFA
XU BIN

Assignees

浙江清华长三角研究院

Dates

Publication Date: 20260512
Application Date: 20260204

Claims (9)

1. The low-carbon preparation method of the bio-based acetic acid is characterized by at least comprising the following steps: Adding non-grain biomass into a pyrolysis unit for pyrolysis carbonization treatment to obtain biochar and bio-combustible gas; adding the biochar into a gasification unit for gasification reaction to obtain synthesis gas; adding the synthesis gas into a separation unit to remove carbon dioxide and separate part of carbon monoxide to obtain a carbon monoxide flow and a reaction gas; Adding the reaction gas into a synthesis unit for synthesis reaction, and adding the synthesis reaction gas into a rectification unit for rectification and purification to obtain refined methanol; Adding the refined methanol into a dehydration unit for dehydration reaction to obtain dimethyl ether; Adding the carbon monoxide flow and the dimethyl ether into a carbonyl inserting unit to perform a carbonyl inserting reaction to obtain methyl acetate; adding methyl acetate into a hydrolysis unit for hydrolysis reaction to obtain a mixed solution; and adding the mixed solution into a purification unit for separation and purification to obtain refined acetic acid.
2. The low carbon production method of bio-based acetic acid according to claim 1, wherein the bio-combustible gas is used at least for heat supply of the pyrolysis unit, the gasification unit, the rectification unit, the dehydration unit and the purification unit.
3. The method for preparing the low carbon of the bio-based acetic acid according to claim 1, wherein the synthesis gas contains hydrogen and carbon monoxide in a molar ratio of 1:1.
4. The method for producing a low carbon bio-based acetic acid according to claim 1, wherein the reaction gas contains hydrogen and carbon monoxide in a molar ratio of 2:1, and the purity of the carbon monoxide stream is not lower than 98%.
5. The method for producing bio-based acetic acid according to claim 1, wherein the carbon dioxide removal operation is performed first in the separation unit and then the carbon monoxide separation operation is performed.
6. The method for producing bio-based acetic acid according to claim 1, wherein the dehydration reaction of methanol and the separation of dimethyl ether are simultaneously performed in the dehydration unit.
7. The method for low carbon production of bio-based acetic acid according to claim 1, wherein the molar ratio of the carbon monoxide stream and the dimethyl ether is 1:1.
8. The method for producing a bio-based acetic acid according to claim 1, wherein the mixed solution is a mixed solution of acetic acid and methanol, the methanol in the mixed solution is removed by separation and purification, and the methanol is recovered to the rectification unit.
9. The method for producing a bio-based acetic acid according to claim 1, wherein the purity of the purified acetic acid is not less than 99.8%.

Description

Low-carbon preparation method of bio-based acetic acid Technical Field The invention relates to the technical field of biomass energy chemical industry, in particular to a low-carbon preparation method of bio-based acetic acid. Background Under the guidance of the 'double carbon' target, the green low-carbon transformation in the chemical industry has become a necessary trend, and acetic acid is one of the organic acids with the largest global use amount, and is widely applied to the production of key chemical products such as vinyl acetate, refined terephthalic acid (PTA), acetate and the like, and the low carbonization of the production process and the green transformation of raw materials become the core direction of industrial technical innovation. Currently, the preparation of industrial acetic acid mainly depends on two main routes: According to the methanol carbonylation method, fossil-based methanol is used as a raw material, a noble metal catalyst such as rhodium and iridium and an iodide promoter are needed, so that the catalyst purchasing and recycling cost is high, the iodide can produce strong corrosion to equipment, high-end corrosion-resistant materials such as hastelloy and titanium alloy are needed, the initial investment and operation and maintenance cost of the equipment are greatly increased, meanwhile, the carbon footprint is high due to the use of fossil raw materials, the environment-friendly risk exists in the recycling treatment of the iodide, and the environment-friendly chemical development requirement is not met. The biological fermentation method takes biomass as a raw material, has a certain carbon neutral advantage, but most of fermentation raw materials are grain resources, have potential contradiction with land competing with grains, have long reaction period and low product concentration, have high energy consumption for subsequent separation and purification, are limited in large-scale production, and are difficult to meet the high-efficiency supply requirement of industrial-grade acetic acid. Biomass is used as renewable resources with rich reserves and neutral carbon, especially non-grain biomass (such as straw, agriculture and forestry waste and the like), and the conversion and utilization of the biomass do not need to occupy grain resources, so that the biomass is an ideal path for getting rid of the dependence of fossil raw materials and realizing deep low-carbon transformation of acetic acid industry. However, the prior art does not form a mature industrial preparation scheme of the non-grain biomass-based acetic acid, and related exploration still faces a plurality of pain points to be broken through urgently: Firstly, the gradient utilization degree of biomass is low, and the low-carbon potential is not fully released. The existing biomass utilization technology focuses on single product conversion, does not perform gradient development of 'energy-raw materials' on non-grain biomass, so that carbon and hydrogen resources in biomass cannot be efficiently split and utilized, part of energy is wasted in a waste heat form, full-chain low carbonization cannot be realized, and a gap exists between the requirement of high-efficiency utilization of resources under the 'double-carbon' target. Secondly, the difficult problem of the suitability of the components of the synthesis gas restricts the process to fall to the ground. If an attempt is made to prepare acetic acid by taking the synthesis gas generated by gasification of non-grain biomass as an intermediate raw material, the problem of adapting the hydrogen-carbon ratio of the synthesis gas needs to be solved firstly, namely, the molar ratio of hydrogen to carbon monoxide in the synthesis gas obtained by gasification of biomass is usually about 1:1, and the hydrogen-carbon ratio needs to be strictly controlled to be 2:1 during synthesis of methanol (a key intermediate step in preparation of acetic acid). The conventional solution in industry is to adjust components by adopting a water gas shift reaction, but the reaction is accompanied by emission of a large amount of carbon dioxide, and extra biomass raw materials are consumed to compensate for carbon loss, so that the energy consumption and the carbon emission are increased, the utilization rate of the raw materials is reduced, and the core logic of low-carbon production is violated. Thirdly, the high cost and high risk hidden trouble of the traditional acetic acid synthesis process are difficult to avoid. Even if the synthesis gas ring is skipped and biomass-derived methanol is directly adopted to prepare acetic acid, the traditional methanol carbonylation technology is still needed, and the bottleneck of high cost and high corrosion cannot be eliminated due to the dependence on noble metal catalysts such as rhodium, iridium and the like and iodide cocatalysts, so that the economical efficiency of the non-grain biomass-based acetic acid is limited. Fourth, there is