稀土等碱性助剂对甲烷部分氧化制合成气整体式Ni/-γAl_2O_3催化剂性能的影响

Partial Oxidation of Methane to Syngas over Monolithic Ni/γ-Al_2O_3 Catalyst——Effects of Rare Earths and Other Basic Promoters

制备了整体式Ni/-γAl2O3和添加稀土等碱性助剂的整体式Ni/-γAl2O3催化剂。研究了温度、烷氧比、空速和助剂等因素对甲烷部分氧化反应性能的影响,并利用XRD和TPR对催化剂进行了表征。结果表明,催化剂活性随着温度的升高而增加;CH4转化率随着烷氧比的增加而降低;当空速为1×105h-1时,整体式催化剂的催化性能最佳。添加碱性助剂Ce,La,Na,Sr均有利于改善催化剂的还原性能,提高催化剂的活性。其中添加稀土Ce,La可使副反应CH4+2 O2→CO2+2H2O完全被抑制,从而使H2选择性达到100%。

A series of monolithic Ni/γ-Al2O3 catalysts with and without basic promoters （ Na, Sr, La, Ce） were prepared. The partial oxidation of methane （POM） to syngas was carried out in a continuous-flow and fixed-bed reactor. The influence of reaction condi- tions （temperature, CH4/O2 ration, space velocity） on the performance of catalyst was investigated. The results demonstrate that at high space velocity of 1 × 105 h^-1, optimal CH4 conversion can be obtained. Effects of promoters such as Na, Sr, Ce, La were also investigated, and the catalyst samples were characterized by means of temperature-programmed reduction （ TPR ） and XRD techniques. XRD suggests that the addition of promoters has no influence on the crystal structure of Ni/γ-Al2/O3 catalyst. The results show that the addition of small amount of promoters improves the reducibility and activity of the catalyst. The side reaction CH4 ＋ 2 O2→CO2 ＋ 2H2O, has been fully restrained and 100% H2 selectivity has been achieved when Ce, La are promoted respectively.