两种甲醇水蒸气重整制氢催化剂的研究

Two kinds of methanol steam reforming catalysts

对采用共沉淀法制备的CuZnAlO类铜系催化剂和采用水滑石类层柱材料(LDHs)前驱体制备的催化剂在甲醇水蒸气重整制氢反应中的性能进行了研究。对共沉淀法制备的CuZnAlO类铜系催化剂考察了ZrO2助剂的加入对催化剂反应性能的影响,发现Zr的质量分数为10%的催化剂显著提高CuZnAlO催化剂的反应性能。该催化剂的最佳反应条件:0.1MPa、250℃、H2O MeOH摩尔比1.0～1.3、3.56h-1。在此反应条件下进行了COPZr 2催化剂150h稳定性实验。结果表明,该催化剂具有很好的反应稳定性。甲醇转化率和氢产率分别约为88%和83%,产物湿基组成中H2和CO的质量分数分别为>63%和0.20%～0.31%。对LDHs前驱体制备的催化剂,进行了70h反应稳定性实验,结果表明,催化剂虽具有较高的起始活性,但随反应进行,活性有所下降,30h后基本保持稳定,甲醇转化率和产氢率分别为73%和66%,产物湿基组成中H2和CO的质量分数分别为>55%和0.07%～0.08%。该类催化剂的反应稳定性虽较差,但却可以显著降低产物湿基组成中CO的摩尔分数。对LDHs前驱体制备的催化剂进行XRD和SEM表征结果表明,ZrO2的加入使催化剂中CuO晶粒分散更为均匀,颗粒更细。

The CuZnAlO catalyst prepared by co-precipitation and the catalyst derived from hydrotalcite-like layered double hydroxides(LDHs) precursors were studied in this paper. For Cu based CuZnAlO, the methanol conversion,H_2 yield and selectivity were improved greatly when ZrO_2 was added as the promoter. COPZr-2 with 10% of Zr shows the best catalytic performance. Its optimized reaction conditions in SRM(steam reforming of methanol) were confirmed as follows: 250℃, 0.1MPa, H_2O/MeOH=1.3, WHSV=3.56h^(-1), no carrier gas. During the 150h stability test of COPZr-2, the methanol conversion and H_2 yield were kept at 88% and 83% respectively; and the H_2 and CO content in outlet were >63% and 0.20%～0.31%, which indicates that the catalysts possess good stability. The catalysts derived from LDHs precursors show high H_2 and CO_2 selectivity.The methanol conversion and H_2 yield are improved when ZrO_2 is added. LDHZr-2 with 30% of Zr shows the best catalytic performance. During its 70h stability test, the activity decreases at first and then methanol conversion and H_2 yield are kept at 73% and 66% respectively; and the H_2 and CO content in outlet are >55% and 0.07%～0.08% respectively, which indicates that such catalysts have good CO_2 selectivity and low outlet CO content. The Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) results of the catalysts derived from LDHs precursors show that ZrO_2-promoter can improve the dispersion of CuO crystals.