CO2加氢被认为是目前固定大量排放CO2的最好方法之一.研发出一种碳纳米管(CNT)促进的Cu-ZrO2-HZSM5沸石分子筛双功能混合型催化剂,将其用于CO2加氢合成甲醇和甲醇脱水生成二甲醚(DME)二步串联催化一器化,实现由(C02+H2)直接合成DME.在5.0MPa,523K,V(H2):V(CO2):V(N2):69:23:8,空速(GHSV)-25000mL/(h·g)的反应条件下,在所研发(Cu2Zr3-10%CNT)-30%HZSM-5催化剂上,CO2加氢的转化率达9.44%,比相应单功能加氢催化剂(Cu:Zr3-10%CNT)的相应值(7.00%)提高35%.CNT能作为Cu-ZrO2-HZSM-5双功能混合型催化剂的促进剂.在上述反应条件下,含CNT的催化剂的DME时空产率达438mg/(h·g),比不含CNT的原双功能混合型基质催化剂的相应值(395mg/(h·g))提高11%.结果证实,利用双功能混合型催化剂,将CO2加氢合成甲醇和甲醇脱水生成DME两个过程串联催化一器化,能大幅度提高CO2加氢转化的效率.
In order to improve the climate conditions,it is desirable to develop methods to convert CO2 into valuable chemicals. Here we report the development of a CNT-promoted Cu-ZrO2-HZSM-5 bi-functional hybrid catalyst, which was used for the "one pot" two-step catalytic synthesis of DME from (CO2 + He ) via CH:~ OH. Over the developed catalyst of (Cu2 Zra-10 ~CNT) 30 ~ HZSM-5 under the reaction conditions of 5.0 MPa,523 K,V(H2):V(CO2):V(Ne)=69:23=8,GHSV=25 000 mL/(h.g),the CO2 hydrogen ation conversion reached 9.44 %. This value was 1.35 times that (7.00 %) of the mono-functional hydrogenation catalyst of Cu2 Zra 10%CNT. The CNT could act as a novel promoter of the Cu-ZrO2-HZSM-5 bi-functional hybrid catalyst. Under the aforementioned reaction conditions,the space-time-yield (STY) of DME reached 438 mg/(h. g) over the CNT-containing bi-functional hybrid cata lyst,which was 1.11 times that (395 mg/(h.g)) of the corresponding CNT-free counterpart. The results of the present work demon- strated that combination of the process for methanol synthesis with that for methanol dehydration to produce DME by using bi-func tional hybrid catalyst could markedly improve the efficiency of CO2 hydrogenation-conversion.