Methanation is a chemical reaction that converts COx to methane through hydrogenation (figure 1). The process for converting CO2 to CH4 was proposed by Paul Sabatier and J.B. Sendersens in 1902. Methanation can turn emitted COx into the valuable energy carrier CH4, potentially creating power-to-gas platform and circular carbon economy. With the rapid development of renewable electricity and power-to-gas technology as an energy-efficient energy storage solution, methanation is being more and more important and gains a lot of attention.
Fig. 1 Chemical equation of methanation reaction
The methanation processes into two categories: i) associative scheme, in which hydrogen atoms are involved in the C–O bond breaking process, and ii) dissociative scheme, where C–O bond breaking takes place before hydrogenation.
The methanation reaction is limited by thermodynamics which is a reversible exothermic reaction. So, it is quite necessary to design catalysts of suitable activity to reach conversions close to equilibrium at moderate reaction temperatures (< 350°C) and high space-velocities.
Methanation catalysts are necessary to lower the high activation barriers and speed up the reaction, and they must fulfil the two requirements: (1) display high efficiency and activity at low temperatures, and (2) remain stable against the reaction heat. The commonly used catalysts in methanation are Ni-based catalysts, Ru-based and many other metal-based catalysts.
The methanation can be used to produce synthetic natural gas (SNG), an efficient energy carrier which could be distributed through the existing infrastructure for natural gas. Nickel-based catalysts are the most thoroughly researched catalysts for CO2 methanation, owing to the abundance of Ni and its low-cost relative to other highly active transition metals (such as ruthenium or rhodium).
Our ALCC-CM series methanation catalysts are suitable for the methanation plant for synthetic natural gas, compressed natural gas, liquefied natural gas and hydrogen purification based on coke oven gas, semi-coke exhaust, low rank coal pyrolysis gas and other raw materials rich in CO, CO2 and H2.
ALCC-CM31 is a traditional medium and low temperature methanation catalyst which uses titanium and rare earth double promoters as additives, resulting in good low-temperature activity and stable activity.
ALCC-CM32 is a medium temperature methanation catalyst which has high content of active components with double accelerators of titanium and rare earth as additives. It has good low-temperature activity and stable activity.
ALCC-CM33 is a high-temperature methanation catalyst with high content of active components and special additives. It can operate stably under high temperature conditions.
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- Other metal-based catalysts
Ruthenium (Ru) is also one of the most reactive methanation catalysts. While catalyst factors, like choice of support, dispersion of metallic Ru on the supports, and inclusion of promoters that enhances the Ru activity, may greatly influence its catalytic ability and CH4 selectivity.
Rhodium (Rh) is the most reactive catalysts for methanation of CO2 at low temperatures (100–200°C). The main benefit of Rh-based catalyst is its lower reduction temperature (less than 400°C) compared to the commonly used Ni-based catalyst.
Numerous evidences suggest good catalytic ability for Pd-based catalysts in CO2 methanation. However, the drawbacks include higher cost of Pd compared to transition metals, low activity, lesser CH4 selectivity, and greater selectivity towards methanol and heavier hydrocarbons.
The synthesis of long-chain hydrocarbons from syngas (CO and H2) by Co catalyst implies that Co does not catalyze water-gas shift reaction. This beneficial characteristic of Co may become disadvantageous for CH4 selectivity during methanation.
Alfa Chemistry is a professional supplier of methanation catalysts. We work together with our customer to develop the specifically required products and then offer catalysts in lab quantities up to large-scale production. For high quality products, professional technical service, and use suggestion, please feel free to contact us.
- Chunghong Tan, Saifuddin Nomanbhay, Abd Halim Shamsuddin, et al. Current Developments in Catalytic Methanation of Carbon Dioxide—A Review. Frontiers in Energy Research, 2021, Volume 9.
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