Study On Preparation Of Alkali Nitrate Catalyst And Photocatalytic Partial Oxidation Ethanol Performance

Ethanol,like methanol,is an important carrier of global carbon cycle and energy cycle in the future,of which the production and utilization have attracted more and more attention.In recent years,the output of ethanol has increased significantly due to the continuous progress of bioethanol technology and ethanol chemical synthesis techniques.Developing new ethanol conversion technologies and converting it into other important chemicals has become a new and hot research topic.Photocatalytic partial oxidation of ethanol,driven by light energy and at mild reaction conditions,is a new green production way,which has important theoretical research significance and practical application potential.Basic bismuth nitrate（Bi₆O₆（OH）₃（NO₃）₃.1.5H₂O）（BHN）is a two-dimensional semiconductor with simple preparation,low cost and low toxicity.Its application in photocatalytic partial oxidation of ethanol expands the application scope of this kind of photocatalyst,enriches the photocatalysis theory and has certain scientific significance.In this paper,ZrO₂ modified BHN was synthesized by one pot hydrothermal method.The effects of hydrothermal conditions on the structure and photocatalytic properties of the catalyst were investigated;Taking the selected optimal catalyst as the carrier,noble metals of Au and Pt,as well as carbon material MWCNT were loaded.The effect of loading on the structure and properties of the catalyst was investigated.The catalyst was characterized by XRD,UV Vis DRS,XPS,BET,TEM,PL and electrochemistry.The photocatalytic oxidation performance of the catalyst driven by ultraviolet light at 25℃-45℃was investigated.The internal relationship between photocatalytic activity and catalyst structure,morphology,light absorption and photochemical properties was analyzed,and the catalytic oxidation mechanism was preliminarily explored.The research results are as follows.1.ZrO₂ and Bi₆O₆（OH）₃（NO₃）₃.1.5H₂O were combined by lattice mismatch growth to form ZrO₂ modified Bi₆O₆（OH）₃（NO₃）₃.1.5H₂O.Compared with BHN,the band gap of Z-BHN changes from 3.22 e V to3.33 e V,and the conduction band edge does not change,but the valence band position is more positive,and thus enhanced the oxidation ability of the photogenerated hole.2.The optimum preparation conditions of Z-BHN were p H 5 at 180℃of the hydrothermal temperature for 20 h with 3:4 of the ratio of ZrO₂:Bi₆O₆（OH）₃（NO₃）₃.1.5H₂O.The catalyst prepared under this condition has ethanol conversion of about 45%,acetaldehyde selectivity of about 80%,ethyl formate selectivity of about 12%and carbon dioxide selectivity of about 6%.The improvement of reaction performance comes from the enhancement of light absorption capacity and photocurrent response of the catalyst,the reduction of impedance,high electron hole pair separation rate and low recombination rate.3.The catalyst loaded with noble metal Au has better photocatalytic activity than that loaded with noble metal Pt.Wherein,the ethanol conversion of 5wt%Au/Z-BHN is 68%,the selectivity of acetaldehyde is84%,the selectivity of ethyl formate is 7.5%,and the selectivity of carbon dioxide is 6.5%.4.Carbon material MWCNT can replace noble metals and improve the performance of Z-BHN catalyst in photocatalytic oxidation of ethanol.Among them,3wt%MWCNT/Z-BHN has the best activity,with ethanol conversion of 57%,acetaldehyde selectivity of 83%,ethyl formate selectivity of 9.5%and carbon dioxide selectivity of 5.8%.The addition of MWCNT accelerates the charge transfer and improves the mobility of photogenerated carrier.