Cu/Ni-based Catalyst Catalyzes Methanol Steam Reforming To Produce Hydrogen

In the research of hydrogen production from alcohols,methanol lacks a strong C=C bond,so methanol steam reforming can produce hydrogen in a relatively low temperature range（200℃-400℃）.Also amount of carbon in methanol is fewer,so the yield of carbon-containing by-products produced in the hydrogen production reaction is relatively low.In terms of catalysts,Cu and Ni-based catalysts have high reactivity and low cost,they are common catalysts of hydrogen production from methanol steam reforming.This study mainly focused on the influence of the precursor of Cu and Ni-based catalysts on the reactivity,and the effects of the ratio of H ₂O/MeOH,support and active metal on the reactivity of Cu-Ni bimetallic catalyst.The results of XRD,BET,H₂-TPR,NH₃-TPD and Raman are used to explain and speculate the results of the catalyst activate test.The overall results are as follows:（1）A series of Cu/Al₂O₃ catalysts were synthesized by impregnation method usi ng copper nitrate,copper chloride and copper sulfate as Cu precursors.The order of reactivity is as follows:copper nitrate>copper chloride>copper sulfate.The main reason is the copper nitrate lost the precursor anion by calcination,but the other two Cu precursors did not lose the precursor anion.Copper chloride and copper sulfate anions have strong acidity,the acidity inhibits the methanol reforming hydrogen production reaction;Subsequently,the Cu/Al ₂O₃ catalyst using copper nitrate as the precurso r was given the time-on-stream test.The catalyst was continuously operating for 26 h and eventually deactivated due to carbon deposition.（2）A series of Ni/Al₂O₃ catalysts were synthesized by using impregnation method using nickel nitrate,nickel acetate,ni ckel chloride and nickel sulfate as precursors of Ni.The order of reactivity was as follows:nickel nitrate>nickel acetate>nickel chloride>Nickel sulfate.On one hand,similaring to the results of the Cu precursor study,SO₄^2-not removed after calcination adversely affects the catalytic performance of the catalyst,and Cl^-is also has bad influence on the catalytic performance of the catalyst during the preparation process.One the other hand,AC anion improved the catalytic performance of the catalyst during the preparation process.Subsequently,the Ni/Al₂O₃ catalyst using nickel nitrate as the precursor was given the time-on-stream test. The catalyst can completely convert methanol for 24h,and then the conversion rate started to drop caused by carbon deposition and eventually last for 30h.（3）Based on the exploration of the best Cu and Ni precursors,Cu-Ni bimetallic catalysts were synthesized by co-impregnation method.The effects of ratio water/MeOH,support and different active metal components on the reactivity of the catalyst were investigated.First,the results show that 3:1 is the best ratio of water/MeOH.Secondly,the reaction ability ofγ-Al₂O₃ and SiO₂ supports was discussed.The result showed that the Cu-Ni-Si catalyst with SiO₂ has stronger ability to convert CH₃OH,but the Cu-Ni-Al withγ-Al₂O₃ has stronger hydrogen production ability.Considering that the main purpose of this study is to produce hydrogen,γ-Al₂O₃ was the best carrier.Finally,the activity of Cu-Ni-Al,Ni-Co-Al,Cu-Co-Al and Cu-Ni-Co-Al synthesized by Cu,Ni and Co was investigated.The order of reactivity was as follows:Cu-Ni-Al>Ni-Co-Al>Cu-Ni-Co-Al>Cu-Co-Al;Cu-Ni-Al containing Cu-Ni alloy to catalyze hydrogen production is higher than that of other alloy catalysts containing Co.This is because the temperature of methanol steam reforming is relatively low（200℃-400℃）,but the Co-containing catalyst requires a higher temperature to exert its full catalytic ability.