Coupling biomass pretreatment for enzymatic hydrolysis and direct biomass-to-electricity conversion with molybdovanadophosphoric heteropolyacids as anode electron transfer carriers

查看全文 作　　者：Huishan [1,2]Yang;Yuchen [1,2]Bai;Denghao [1,2]Ouyang;Fangqian [1,2]Wang;Dehua [1,2]Liu;Xuebing [1,2]Zhao 机构地区：[1]Key Laboratory of Industrial Biocatalysis,Ministry of Education,Tsinghua University,Beijing 100084,China;[2]Institute of Applied Chemistry,Department of Chemical Engineering,Tsinghua University,Beijing 100084,China 出　　处：《Journal of Energy Chemistry》索引2021年第30卷第7期,共14页 基　　金：supported by the National Key Research and Development Program of China(2018YFA0902200);the National Natural Science Foundation of China(No.21878176)。 摘　　要：Owing to their acidity,oxidizing ability and redox reversibility,molybdovanadophosphoric heteropolyacids(H_(n+3)PMo_(12-n)VnO40,abbreviated as PMo_(12-n)Vn) were employed as electron transfer carriers for coupling biomass pretreatment for enzymatic hydrolysis and direct biomass-to-electricity conversion.In this novel coupled process,PMo_(12-n)Vn pretreatment that causes deconstruction of cell wall structure with PMo_(12-n)Vn being simultaneously reduced can be considered as the 'charging' process.The reduced PMo_(12-n)Vn are further re-oxidized with release of electrons in a liquid flow fuel cell(LFFC) to generate electricity is the 'discharging' process.Several Keggin-type PMo_(12-n)Vn with different degree of vanadium substitution(DSV, namely n) were prepared.Compared to Keggin-type phosphomolybdic acid(PMo_(12)),PMo_(12-n)Vn(n=1-6) showed higher oxidizing ability but poorer redox reversibility.The cellulose enzymatic digestibility of PMo_(12-n)Vn pretreated wheat straw generally decreased with increase in DSV, but xylan enzymatic digestibility generally increased with DSV.PMo_(12) pretreatment of wheat straw at 120℃ obtained the highest enzymatic glucan conversion(EGC) reaching 95%,followed by PMo11V1 pretreatment(85%).Discharging of the reduced heteropolyacids in LFFC showed that vanadium substitution could improve the maximum output power density(Pmax).The highest Pmax was obtained by PMo9 V3(44.7 mW/cm^(2)) when FeCl_(3) was used as a cathode electron carrier,while PMo_(12) achieved the lowest Pmax(27.4 mW/cm^(2)).All the heteropolyacids showed good electrode Faraday efficiency(>95%) and cell discharging efficiency(>93%).The energy efficiency of the coupled process based on the heat values of the products and generated electric energy was in the range of 18%-25% depending on DSV.PMo_(12) and PMo11V1 seem to be the most suitable heteropolyacids to mediate the coupled process. 关 键 词：Molybdovanadophosphoric heteropolyacid Electron transfer carrier Biomass pretreatment Enzymatic hydrolysis Direct biomass fuel cell Electricity generation