Chemicals

Catalysts for methanol synthesis

The aim of the project is to improve catalysts for methanol synthesis in terms of throughput, stability and selectivity. The project provides results regarding microstructural properties as well as regarding synthesis procedures and conditions for Cu/Zn/Al catalysts. The results thus contribute to increasing the usage efficiency of sustainable resources, e.g. biogas or syngas.

Summary

Methanol is capable of replacing mineral oil as an energy carrier and petrochemical resource. It can be synthesised, for example, from natural gas, petroleum gas or biogenic syngas (CO/H2) such as is produced by the gasification of waste products. Methanol can then be employed as the energy carrier in fuel cells. This project aimed to develop Cu/Zn/Al catalysts for methanol synthesis and to optimise them in terms of throughput, selectivity and stability at reduced reaction temperatures. To this end, seven Cu/Zn/Al samples were examined in regard to properties important for catalysis. The goal was to optimise the synthesis parameters of nitrate-based synthesis (mixed metal-nitrate solution for coprecipitation) and of formate-based synthesis (formate solution for coprecipitation) for production of catalysts. Sequential precipitation of Cu/Zn/Al source products was examined by varying the precipitation sequence.
Improvement of the catalysts is intended to facilitate break-even use of petroleum gas and biomass and to initiate innovations in the field of fuel and fuel cells.
Results:

  • The high activity of individual catalyst samples results from their specific microstructure; porous copper aggregates and oxide nanoparticles created within the malachite-like precursor of the catalysts lead to coherency strain and high defect density and provide a beneficial effect on activity.  
  • For synthesis of catalysts based on nitrates, a temperature of 60 to 70 °C and pH 6 to 7 is particularly well-suited for precipitation and ageing. A synthesis procedure was reproducibly implemented using an automatic laboratory reactor system.
  • In nitrate-based synthesis, a ratio of Cu:Zn:Al of 86:29:3 leads to the highest levels of substitution (inclusion of aluminium) within the malachite precursor. This leads to a highly homogeneous distribution of aluminium in the resulting catalyst. Using greater Al content is detrimental to the desired, high substitution level. 
  • In terms of activity, the formate-based samples examined display superior properties to most of the nitrate-based samples. This is due to the high substitution level of the malachite phase.
  • Ternary precipitation achieves a significantly lower specific copper surface (activity indicator) than ternary precipitation with simultaneous copper, zinc and aluminium precipitation.
  • The high-throughput test also developed as part of the project, which supplies data on the stability of the catalyst, as well as ageing tests in which the catalysts are subjected to oxidisation and reduction cycle loads showed that the synthesised catalyst displays greater stability than conventional catalysts.

More Project Informations

Project title: Verbundvorhaben 'Entwicklung von Methanolsynthesekatalysatoren als Basis für nachhaltige Ressourcennutzung

Project number: 01RI05027- 01RI05029

Project period: 2005 - 2008

Project region: Germany (Berlin, Bavaria, North Rhine-Westphalia)

Project contact:

Herr Dr. Behrens
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View Publication

Source: German National Library of Science and Technology Hannover (TIB)