The impact of components of synthesis gas from coal gasification on conversion of model tar compounds over Ni/CeZrO2 catalyst

Coal gasification is accompanied with formation of tars that cause equipment problems and have to be removed from the raw gas. Our previous studies proved that nickel supported ceria-zirconia catalyst (Ni/CZ) reveals high activity towards decomposition of toluene and 1-methylnaphthalene (1-MN) via steam reforming reaction (SR). However, the components of the raw gas from coal gasification (i.e. H-2, CO, CO2 and CH4) may influence the performance of Ni/CZ catalyst. The influence of particular components of the raw gas on catalyst performance during SR of model tar compounds have been studied and discussed in this paper. It has been found that H-2 and CO addition to the steam reforming feed drastically decreases the activity of Ni/CZ catalyst, whereas CO2 presence enhances conversion of toluene and 1-MN mixture owing to the occurrence of dry reforming reaction (DR). It has also been observed that methane, which is present in the raw gas from coal gasification consumes partly both the H2O and CO2, causing some decrease in conversion of model tar compounds. The influence of contact time (t(c)) on hydrocarbons conversion and the participation of (DR) have been examined. As was observed, lower contact times lead to decrease in hydrocarbons conversion in SR, making the same participation of DR more pronounced than for higher tc values. This work proves that Ni/CZ catalyst can be used for removal of tarry compounds via the catalytic hot gas cleaning of the raw gas form coal gasification.