Experimental study on high-purity hydrogen generation from synthetic biogas in a 10 kW fixed-bed chemical looping system

Abstract

Experimental proof of synthetic biogas utilization for high-purity hydrogen generation (99.998%) with a 10 kW fixed-bed chemical looping system.

Co-production of pure hydrogen, carbon dioxide and nitrogen in a 10 kW fixed-bed chemical looping system

“…However, in both cycles, a steady-state steam conversion of 66-74% was attained with respect to a feed gas ow of 24.2 g min À1 (30 NL min À1 ), which is consistent with the Bauer-Glaessner diagram and previous experimental series. 15,16 Carbon monoxide and carbon dioxide were found as trace gas compounds in the product gas, and methane was successfully excluded by the evacuation of the reactor system beforehand. In the rst experimental cycles (cycles 1-10), relatively high gas remnants were still present in the product gas conditioning system aer the purging phase.…”

“…According to previous experimental investigations, 15,16 three different gas mixtures were specied as a reducible gas feed ( Table 1). The rst composition represented a typical steam reforming feed gas comprising methane and steam with an S/C ratio of 1.2 (¼O/R ratio).…”

“…Hacker et al included a steam reformer and a xed-bed chemical looping section within a single reactor, which enables concurrent hydrogen production and purication 12,13 with an efficiency of up to 73% according to thermodynamic studies. 14 Based on this scheme, a 10 kW lab system was presented by our research group for the conversion of methane and synthetic biogas with a capacity of up to 20 kg oxygen carrier in combination with an upstream steam reformer for syngas generation 15,16 (see Fig. 1).…”

“…According to recent studies, a minimum amount of excess steam has to be co-fed to avoid harmful carbon deposition. 16,17 In recent years, various studies have been presented on the conversion of different fossil and bio-based raw materials to hydrogen using chemical looping in small scale lab systems and great efforts have been made to enhance the material lifetime and kinetics. 10,11,18 Several research groups also demonstrated the utilization of chemical looping processes for hydrogen generation with inherent carbon dioxide sequestration from fossils as gasied coal, methane or renewables as gasied biooils in enlarged systems, most of them in uidized bed operation.…”

“…The utilization of both fossil and renewable feedstocks is possible to either produce hydrogen as a secondary energy carrier, while inherently sequestrating carbon dioxide for CCS or CCU from fossil resources, or even represents a negative emission technology by using renewable feedstocks for bioenergy carbon capture and storage (BECCS). Based on previous ndings, 15,16 the impact of two synthetic biogas compositions and methane as feedstock on the process applicability was determined. The experimental study was performed in the largest 10 kW xed-bed chemical looping research system currently available worldwide.…”