Study Of Syngas Generation From Carbon Dioxide And Water Co-electrolysis In Molten Salts

The extreming global climate change deriving from vast CO₂ emission has been cited as one of the major issues which are urgently to be solved,attracting increasing attention of governments,experts and the public.Currently,main strategies for yielding CO₂ emission are focused on carbon capture and storage,and the resource utilization of CO₂ has a broad prospect.This project proposes one novel syngas（H₂+CO）generation pathway from CO₂/H₂O co-electrolysis in molten salts,which achieves high value-added utilization of CO₂and realizes the controllable synthesis of syngas with desirable H₂/CO ratio.This project implements the thermodynamic calculation of CO₂/H₂O electrochemical reaction of molten salts system,the thermal stability analysis of electrolyte,tests the transformation of CO₂/H₂O in molten salts electrolyte electrode process,determines the optimal composition of molten salts electrolyte and electrolysis conditions,studies the mole ratio of hydrogen and carbon（n_H:n_C）on the effect of H₂/CO mol ratio in the syngas.The cyclic voltammetry curve proves that CO₂/H₂O can produce an electric reduction reaction in the molten salts system.The reduction products are CO,CH₄ and H₂,respectively,and the oxidation product is O₂.Based on the analysis of current efficiency and products distribution under varying hydroxides and carbonates composition,Li_0.85Na_0.61K_0.54CO₃ system was considered as the optimum mixed carbonate,and LiOH was determined as the optimal source of hydrogen.Thermal endurance experiments show that Li_0.85Na_0.61K_0.54CO₃/LiOH demonstrates an excellent stability at applied high temperature range.At applied potential of2.5 V,operating temperature of 450°C,Ni wire and Fe wire as anode and cathode respectively,the synthesized syngas contains very desirable content of H₂ and CO,whose molar ratio（H₂/CO）could be facilely tuned from 0.50 to 12.28,achieving the controllable synthesis of syngas.Using low-product-order renewable electricity to electrolyze CO₂/H₂O in molten salts medium to synthesize syngas fuel could turn waste into wealth,achieve the resource utilization of CO₂ exhaust,and meet industrial raw material demand.