Catalytic gasification of wet municipal solid waste with HfO_2 promoted Ni-CaO catalyst for H_2-rich syngas production

摘要

Catalytic gasification, coupled with in-situ CO2 capture over Ni-CaO catalyst, is considered to be an effective approach for H-2-rich and tar-free syngas production. However, the poor stability of Ni-CaO based catalyst raises a question regarding its large scale application. In this study, HfO2 was used as a stabilizer and promoter for the NiCaO catalyst system. The stability of catalyst was evaluated through cyclic carbonation-calcination test with a thermogravimetric analyzer. The results showed that HfO2 incorporated catalysts performed better stability towards cyclic CO2 capture. The effect of different HfO2 additions in catalyst, catalyst to municipal solid waste (C/MSW) ratio, gasification temperature, and moisture content (MC) of MSW was investigated on syngas composition, H-2 yield, dry gas yield (DGY) and product distribution (syngas, tar and char). The results indicated that H-2 yield was improved from 212 mL/g (without catalyst) to 442 mL/g with Ni-CaO (NC) catalyst and further improved with the application of HfO2 promoted catalysts (Ni-CaO-HfO2). The catalyst with 20% HfO2 (NCH-20) exhibited maximum H-2 yield of 597 mL/g. Moreover, a significant reduction in tar content from 8.79 wt% (without catalyst), 3.19 wt% (with Ni-CaO) to 2.81 wt% (with NCH-20) was also recorded with HfO2 promoted catalysts.