Methanol synthesis catalysts

Methanol, also known as wood alcohol or wood sperm, is a volatile liquid with a colourless, slightly ethanolic aroma, which is highly toxic and easily combustible. Methanol is second only to synthetic nitrogen as a chemical product and is the basic substance of carbon I chemistry. Methanol is an important organic chemical raw material and solvent, and is an indispensable raw material and solvent in the three major synthetic materials, pesticides, pharmaceuticals, dyes, fragrances and paints industries. With the world's energy constraints, methanol has attracted attention worldwide as an alternative clean fuel. In recent years, the consumption of methanol as an energy source has increased significantly, which has led to the development of the methanol industry. In addition, methanol is a good raw material for the synthesis of proteins and direct synthesis of acetic acid.

Chemical reaction principle

CO, CO2 and H2 react under pressure and in the presence of a catalyst to form methanol and a series of side reactions.

Primary reaction:

CO+2H2----CH3OH                      ΔH298 = -90. 64kJ/mol

CO2+3H2-----CH3OH+H2O         ΔH298 = -49. 47kJ/mol

Side reactions:

CO+3H2-----CH4+H2O

2CO+4H2----C2H5OH+H2O

2CO+4H2 ----CH3OCH3+H2O

The reaction between CO and H2 to produce methanol is a volume-reducing, strongly exothermic reaction whose heat of reaction is not only related to the reaction temperature, but also to the reaction pressure. The synthesis of methanol is a multiphase catalytic reaction process and the reaction rate is not only related to the reaction conditions, but also to the catalyst. Therefore, a catalyst with both high selectivity and good activity must be selected, while controlling the appropriate temperature and pressure to move the reaction in a direction favourable to methanol synthesis.

The development of catalysts for methanol synthesis is a cornerstone of the synthesis industry and can be divided compositionally into four categories: zinc-chromium based catalysts, copper based catalysts, non-copper based catalysts and liquid phase catalysts.