A device and method for preparing aromatics by coal staged hydropyrolysis

Abstract

The present invention provides a device and method for preparing aromatics by coal staged hydropyrolysis. The device includes a primary hydropyrolysis reactor, a secondary hydropyrolysis reactor, a hydrogen pyrolysis product separation unit, Hydrogen pyrolysis product fractionation unit and mixed aromatics hydrogenation device; the outlets of the primary hydropyrolysis reactor and the secondary hydropyrolysis reactor are independently connected with the hydropyrolysis product separation unit, hydropyrolysis The product fractionation units are connected in sequence, the mixed aromatics outlet of the hydropyrolysis product fractionation unit is connected to the mixed aromatics hydrogenation unit, the medium oil outlet is connected to the second-stage hydropyrolysis reactor, and the heavy distillate oil outlet is connected to the first-stage hydropyrolysis reaction connected to the device. The present invention adopts molecular segmentation technology to produce aromatics by graded hydropyrolysis, and introduces a hydrogen-supplying solvent in the process of coal hydropyrolysis to realize directional transformation of material structure and greatly improve the yield of aromatics; the method has a short process flow , High utilization rate of raw materials and energy efficiency, get rid of the dependence of aromatics on petroleum resources.

Description

technical field [0001] The invention belongs to the technical field of coal chemical industry, and relates to a device and method for preparing aromatics by coal classification and hydrogen pyrolysis. Background technique [0002] With the rapid development of the economy, people's demand for various chemical raw materials is also increasing. Among them, BTX (benzene, toluene, xylene) and other single-ring aromatic hydrocarbons, as important basic chemical raw materials, have been long-term demanded products in the market. Aromatics, as an important chemical raw material, are mainly obtained industrially through petroleum-based naphtha catalytic reforming and naphtha steam cracking processes. This process has a long process flow and low product yield. In view of my country's energy structure characteristics, If the existing raw material route is still used for the production of aromatics, it will face the challenge of tight supply of petroleum raw materials, and at the same t...

AI Technical Summary

Problems solved by technology

Aromatics, as an important chemical raw material, are mainly obtained industrially through petroleum-based naphtha catalytic reforming and naphtha steam cracking processes. This process has a long process flow and low product yield. In view of my country's energy structure characteristics, If the production of aromatics still uses the existing raw material route, it will face the challenge of tight supply of petroleum raw materials, and at the same time cause the price of downstream products to remain high. Therefore, it is necessary to vigorously develop the process technology for producing aromatics with coal as raw material

[0003] At present, the routes for producing aromatics from coal mainly include the following: 1) The crude benzene produced by coal coking or the crude naphtha rich in BTX produced by the fixed bed coal gasification process is processed by hydrotreating and aromatics extraction. However, the yield of crude benzene or crude naphtha in the above process is low, and the further production of BTX is limited by the main product, so it cannot be used in the production of aromatics products on a large scale, and can only be used as a coal-to-aromatics product. Supplement; 2) Methanol is produced by coal gasification, and then BTX is produced by methanol aromatization and aromatics extraction. , dehydrogenation, the overall utilization rate of carbon atoms is low, and energy consumption is high; 3) Coal gasification produces methanol, and then produces p-xylene through toluene methylation technology. This method cannot completely get rid of the dependence on petroleum resources, and the utilization rate of methanol 4) Low-temperature pyrolysis of coal to produce coal tar, followed by hydrofining / cracking, catalytic reforming of naphtha, and extraction of aromatics to produce BTX products. This process is long and requires repeated aromatics Hydrogenation saturation and cycloalkane reforming dehydrogenation reaction, low yield of aromatics, low energy efficiency utilization

[0004] CN 101280207A discloses a method for direct liquefaction and comprehensive utilization of low-quality coal. Coal powder and a hydrogen-donating solvent undergo a series of liquefaction reactions such as pyrolysis, dissolution, and hydrogen transfer under pressurized and heated conditions, and form a liquefaction product after three-phase separation. Gas, oil and residue are generated, the residue undergoes gasification hydrogen production reaction, the liquefied gas is condensed and separated, and the liquefied oil is distilled and separated to obtain aromatic-rich gasoline, diesel oil, etc.; the liquefaction reaction products of the method are complex, and the liquid phase products The proportion is not high, resulting in a low yield of aromatic oil, and it is impossible to produce a large amount of aromatics from coal

[0005] CN 107216896A discloses a system and method for preparing light aromatics from pulverized coal with heavy aromatics recycling function, including fast pyrolysis device, purification and separation device, mixing tank, mixing tank, filter, ball pressing device, calcium carbide Furnace, acetylene generator, acetylene-to-aromatics reactor and separation system, through pyrolysis of pulverized coal, semi-coke, pyrolysis gas and coal tar are obtained, acetylene product gas is prepared from semi-coke, and then acetylene product gas, carbon monoxide, hydrogen, Methane undergoes thermal and catalytic reactions to prepare aromatic products, and the heavy aromatics obtained after the separation of aromatic products can dilute coal tar; this method still uses the traditional pulverized coal pyrolysis process, which is made from semi-coke and then undergoes multi-step reactions. Aromatics, the process is complex and energy-intensive

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