CN-122003395-A - Method for preparing methanol by using renewable raw materials and/or energy sources

Abstract

The present application relates to a process for the preparation of methanol comprising the steps of (a) providing an amount of methanol synthesis gas comprising hydrogen, carbon monoxide and carbon dioxide, (b) introducing the amount of methanol synthesis gas into at least one methanol reactor, (c) catalytically reacting at least a portion of the methanol synthesis gas to methanol, (d) withdrawing the produced methanol from the at least one methanol reactor and sending the produced methanol to a methanol storage unit, (e) reducing the amount of methanol synthesis gas introduced into the at least one methanol reactor and sending methanol products from the methanol storage unit to a catalytic methanol cracking unit, (f) cracking a portion of the withdrawn methanol products into cracked methanol synthesis gas in the catalytic methanol cracking unit, and (g) adding the cracked methanol synthesis gas in step (f) to the reduced amount of methanol synthesis gas in step (e).

Inventors

• P.J. Dar

Assignees

• 托普索公司

Dates

Publication Date

20260508

Application Date

20241021

Priority Date

20231030

Claims (5)

1. 1. A process for the preparation of methanol comprising the steps of: (a) Providing an amount of methanol synthesis gas comprising hydrogen, carbon monoxide and carbon dioxide; (b) Introducing the amount of methanol synthesis gas into at least one methanol reactor; (c) Catalytically reacting at least a portion of the methanol synthesis gas to produce methanol; (d) Withdrawing the produced methanol from the at least one methanol reactor and sending the produced methanol to a methanol storage unit; (e) Reducing the amount of methanol synthesis gas introduced into the at least one methanol reactor and passing methanol product from the methanol storage unit to a catalytic methanol cracking unit; (f) Cracking a portion of the withdrawn methanol product in a catalytic methanol cracking unit to cracked methanol synthesis gas, and (G) Adding the cracked methanol synthesis gas of step (f) to the reduced amount of methanol synthesis gas of step (e).
2. 2. The process of claim 1, wherein the amount of methanol synthesis gas is produced by means of a renewable resource.
3. 3. The method of claim 2, wherein the renewable resources comprise gasified biomass, captured carbon dioxide, and electrolytically-generated hydrogen.
4. 4. The process according to any of the preceding claims, wherein the amount of methanol synthesis gas introduced into the at least one methanol reactor in step (e) is reduced by up to at least 80%, such as 85%, 90%, 95% or up to 100% compared to the full methanol synthesis gas duty of the at least one methanol reactor.
5. 5. The process of any of the preceding claims, wherein in step (f) methanol is cracked to provide in step (g) a combination of at least 10% methanol synthesis gas and plus cracked methanol synthesis gas.

Description

Method for preparing methanol by using renewable raw materials and/or energy sources The present invention relates to a process for the preparation of methanol using renewable raw materials and/or energy sources. More specifically, the present invention utilizes the cracking of the methanol produced to provide additional methanol synthesis gas in the event of a feedstock or energy supply shortage. As one example, synthesis gas has traditionally been produced by subjecting natural gas or higher hydrocarbon feedstock to an endothermic steam reforming reaction in a combustion tubular steam reformer by contact with a steam reforming catalyst. The primary reformed gas is then fed to a secondary adiabatic reformer in which a portion of the hydrogen and a residual amount of hydrocarbons in the gas are partially oxidized with oxygen in the presence of a secondary reforming catalyst. In large methanol synthesis plants, primary and secondary steam reforming may be replaced by autothermal reforming (ATR). In recent years, the use of renewable energy sources or feedstocks in methanol synthesis has become more common. As one example, water is hydrolyzed using renewable energy sources such as wind and solar energy to produce hydrogen by water electrolysis, in combination with carbon dioxide from a carbon capture or other carbon oxide source. The hydrogen and carbon dioxide thus produced are combined in stoichiometric proportions to form synthesis gas for methanol production. A problem with using renewable raw materials in methanol synthesis is that the supply of energy and/or renewable raw materials fluctuates depending on, for example, natural variations in wind and sunlight or the supply of external carbon oxides. Thus, the flow of fresh methanol synthesis gas produced by means of renewable raw materials can fluctuate considerably. In order to replace the converted hydrogen and carbon oxides in the unconverted synthesis gas, fresh synthesis gas must be added continuously to the loop recycle gas (loop RECYCLE GAS) as make-up gas. At low power and/or low syngas (h2+cox) availability, it is still necessary to keep methanol synthesis at a load of at least 10%. The term "Cox" refers to CO and CO2. Power is required for hydrogen generation, whereas COx is required for methanol synthesis. The invention reduces the power consumption required at minimum synthesis load and eliminates the need for imported CO2, CO. MeOH has been proposed for use in power generation in fuel cells, or by combusting MeOH and converting thermal energy into power. There is no standard solution for loss of COx. We have found that in the event of a feed gas shortage, the amount of feed gas to the methanol reactor can be controlled by cracking a portion of the produced methanol to methanol synthesis gas and adding the synthesis gas thus produced to the incoming feed gas. This ensures the availability of H 2 and Cox compared to using methanol to generate power and then using that power to generate hydrogen. Less power is required to produce hydrogen from the cleavage of methanol than is produced from MeOH and then using that power to produce hydrogen. In addition, COx is required in methanol synthesis gas. If the COx feed supply is interrupted, meOH production is stopped. The cracked methanol gas contained COx and had the correct composition for MeOH synthesis. Thus, the present invention reduces the power consumption required at minimum synthesis load and eliminates the need for inlet COx by using a methanol cracker to produce the required synthesis gas. The cracker can be operated continuously at a load corresponding to 10% of the amount of methanol synthesis supported. Methanol cracking is the process of decomposing methanol into hydrogen and COx. The process of methanol cracking typically involves heating methanol to an elevated temperature in the presence of a catalyst. The catalyst helps to promote the reaction and increase the yield of cracked methanol synthesis gas. The cracked methanol gas contains COx and has the correct composition for methanol synthesis. Preferred embodiments of the present invention are as follows. 1. A process for the preparation of methanol comprising the steps of: (a) Providing an amount of methanol synthesis gas comprising hydrogen, carbon monoxide and carbon dioxide; (b) Introducing the amount of methanol synthesis gas into at least one methanol reactor; (c) Catalytically reacting at least a portion of the methanol synthesis gas to produce methanol; (d) Withdrawing the produced methanol from the at least one methanol reactor and sending the produced methanol to a methanol storage unit; (e) Reducing the amount of methanol synthesis gas introduced into the at least one methanol reactor and passing methanol product from the methanol storage unit to a catalytic methanol cracking unit; (f) Cracking a portion of the withdrawn methanol product in a catalytic methanol cracking unit to cracked methanol synthesis gas, and (G) Addi