Cu/Zn比对微波辐射老化制备CuO/ZnO/Al_2O_3催化剂结构和活性的影响

Effects of Cu/Zn on the Structure and Activity of CuO/ZnO/Al_2O_3 Catalysts Prepared under Microwave Irradiation in Aging Process

在微波辐射条件下,对共沉淀法制备合成甲醇CuO/ZnO/Al2O3催化剂前驱体的母液进行老化,通过改变Cu/Zn比,研究了微波辐射对催化剂性能的影响,并结合XRD,FTIR,DTG,H2-TPR,XPS等表征手段,探讨了微波辐射对前驱体物相组成及催化剂微观结构的影响.结果表明:在微波辐射老化条件下,Cu/Zn比对催化剂前驱体物相组成影响较大,微波辐射有利于绿铜锌矿(Cu,Zn)5(CO3)2(OH)6晶相选择生成.当Cu/Zn比为2.0时,前驱体中含有较多的绿铜锌矿物相,且结晶较好,焙烧后形成的催化剂中CuO-ZnO协同作用较强,CuO分散性好,导致H2还原温度低,在浆态床合成甲醇过程中表现出良好的催化活性和稳定性,甲醇时空收率(STY)达到309.0 g·kg-1·h-1,失活率仅为0.11%/d,远优于常规水浴加热制备的催化剂.

Microwave irradiation was introduced into the aging process of co-precipitation to prepare CuO/ZnO/Al203 catalyst precursor in this paper. Influence of Cu/Zn on catalytic performance was investigated under microwave irradiation, the effects of microwave irradiation on phase composition and catalyst structure were illuminated by use of X-ray diffraction （XRD）, FT-IR spectroscopy （FT-IR）, derivative thermogravimetry （DTG）, H2 temperature programmed reduction （H2-TPR） and X-ray photoelectron spectroscopy （XPS）. It indicated that the ratio of Cu to Zn had important effect on catalyst, microwave irradiation benefited to the formation of （Cu, Zn）5（CO3）2（OH）6 in the precursor. The precursor possessed more （Cu, Zn）5（CO3）2（OH）6 as the ratio of Cu to Zn was 2.0, it exhibited well synergy, well dispersion, low reduce temperature after calcination, which benefited to slurry methanol synthesis, its methanol space-time yield （STY） and deactivation rate of the catalyst were 309.0 g·kg^-1 ·h-^1and 0.11%/d respectively, which excelled the catalytic performance of catalyst prepared by water heating.