Abstract
The stepwise conversion of CH4 to higher hydrocarbons over HMCM-22 zeolite supported metal-boron amorphous alloy catalysts has been investigated, including: (1) the influence of metals (Co, Ni, Pt, Rh and Ru) of the catalysts on the reaction; (2) the promotional effect of V on the catalytic behavior of the catalysts; (3) the influence of hydrogenation pressure and CH4 decomposition temperature; and (4) the nature of carbon species. It is found that the yield of C2+ hydrocarbons is strongly dependent on the metals. Good yields of C2+ hydrocarbon are reached only on the supported NiB and CoB catalysts. The probability of C-C chain growth is increased by V promotion without seriously affecting the activities of CH4 decomposition and hydrogenation. The ease of carbon removal via hydrogenation is strongly affected by the CH4 decomposition temperature. Increasing hydrogenation temperature has a negative effect on the yield of C2+ hydrocarbons. XPS measurements show that a carbide-(like) carbon species is active and selective for hydrogenation to produce higher hydrocarbons. Its activity/selectivity is greatly reduced at high CH4 decomposition temperatures, mainly due to transition of the reactive carbidic to un-reactive graphitic form. Graphite/filamental carbons were found to be formed at high CH4 decomposition temperature.
| Original language | English |
|---|---|
| Pages (from-to) | 231-237 |
| Number of pages | 7 |
| Journal | Catalysis Letters |
| Volume | 78 |
| Issue number | 1-4 |
| DOIs | |
| State | Published - Mar 2002 |
| Externally published | Yes |
Keywords
- Amorphous alloy catalyst
- Carbon
- Higher hydrocarbon formation
- Hydrogen production
- Hydrogenation
- Stepwise conversion of methane
