K_2O助剂对合成碳酸二甲酯用Cu-Ni/MoO_3-SiO_2催化剂吸附和反应性能的影响

用等体积浸渍法制备了MoO3 SiO2 (MoSiO)表面复合氧化物负载的Cu Ni K2 O催化剂。利用IR ,TPR ,TPD以及微反技术研究了K2 O助剂对CO2 和CH3OH在Cu Ni MoSiO催化剂表面上吸附和合成DMC(碳酸二甲酯 )反应性能的影响。结果表明 :K2 O助剂的加入 ,使CO2 在催化剂表面吸附强度增加 ,当K2 O含量达Cu Ni总量的 15 %时 ,CO2 在催化剂表面上吸附后生成K2 CO3;CH3OH在催化剂表面上的解离吸附态 (CH3O- H )的吸附强度减弱 ;CO2 和CH3OH在Cu Ni K2 O MoSiO催化剂表面反应主要产物为DMC ,H2 O ,CO和CH2 O。随着K2 O助剂的加入 ,反应转化率在 10 %之前增加 ,之后下降 ,DMC选择性稍有提高。副产物 (CO和CH2 O)的选择性下降。根据实验结果探讨了K2 O对催化剂表面活性中心的电荷分布的影响。

EFFECT OF K_2O ON ADSORPTION AND REACTION ON Cu-Ni/MoO_3-SiO_2 CATALYST FOR THE SYNTHESIS OF DIMETHYL CARBONATE

MoO 3 SiO 2(MoSiO) supported Cu Ni K 2O catalysts for the synthesis of dimethyl carbonate were made using isovolumic impregnation Based on IR, TPR, TPD and micro reactor techniques, the effect of K 2O on adsorption and reaction of CO 2 and CH 3OH on catalyst were characterized The results show that the addition of K 2O exerts obvious influence on the charge distribution of active sites on Cu Ni/ MoSiO catalyst The K 2O addition increases the intensities of CO 2 horizontal adsorption state while the dissociation state of methanol descends When the K 2O content is above 15%, K 2CO 3 is formed on the catalyst Moreover, the main reaction products of CO 2 and CH 3OH on Cu Ni K 2O/ MoSiO catalyst are still DMC, H 2O, CO and CH 2O With the addition of K 2O, the conversion of reactants and the selectivity of DMC rise, but the selectivity of by products decreases