Zn引入对DME合成催化剂性能的影响

Effect of Zn on performance of catalyst for DME synthesis

通过沉淀法在介孔Al_2O_3上负载铜基催化剂,制备了Cu/Al_2O_3和Cu/Zn/Al_2O_32种催化剂,并用以研究Zn引入对催化剂性能的影响。通过XRD、H2-TPR、CO2和NH3-TPD对催化剂结构和物化性能进行表征。结果表明,Zn引入使得催化剂前驱体中形成了新相:Cu3Zn3Al2(OH)16CO3·4H2O,前驱体焙烧后形成了较小CuO颗粒,还原后Cu颗粒仍然很小,从而增加了Cu的分散度和表面积,明显降低了Cu物种还原难度。Zn引入还明显增加了强碱位和强酸位数量,使得气体转化率达到86. 39%,DME时空收率达到7. 33 mmol/(g·h)。稳定性实验表明,Zn的引入提升了催化剂稳定性。

Cu/Al2O3 and Cu/Zn/Al2O3 catalysts are prepared through loading copper-based catalysts on mesoporous Al2O3 by precipitation method and is used to study the effect of Zn addition on catalyst performance.The structure and physicochemical properties of these catalysts are characterized by XRD,H2-TPR,CO2 and NH3-TPD.The results show that the addition of Zn causes a new phase,Cu3 Zn3 Al2(OH)16 CO3·4 H2O,to form in the catalyst precursor.Smaller Cu O particles are formed after roasting the precursor and Cu particles still remains small after reduction,thus increasing the copper dispersion and surface area,and decreasing the difficulty of Cu species reduction.The addition of Zn also increases significantly the numbers of strong base and strong acid sites,promoting the gas conversion to reach86.39%and DME space-time yield to reach 7.33 mmol/(g·h).The stability experiment shows that Zn can improve the stability of catalyst.