CH_4、CO_2与O_2制合成气催化剂研究 VI.催化剂表面积炭种类和积炭动力学研究

Catalysts for Catalytic Forming of CH_4, CO_2 and O_2 to Syngas Ⅵ. Carbon Spices on the Catalysts Surface and Carbon Deposition Kinetics

利用XPS考察了甲烷、二氧化碳和氧气制合成气反应前后Ni/γ-Al2O3和Ni-Ce-Mn-Li/γ-Al2O3催化剂表面炭物种.发现反应后Ni/γ-Al2O3催化剂表面积炭有四种类型-表面碳酸盐、污染炭、金属炭化物和非活性炭,而高活性和稳定性Ni-Ce-Mn-Li/γ-Al2O3催化剂表面积炭仅有两种类型——污染炭和金属炭化物.非活性炭是导致催化剂失活的主要原因之一.积炭动力学研究表明:Ni-Ce-Mn-Li/γ-Al2O3催化剂上积炭反应的动力学方程为:-0.45·PO2-1.80,该催化剂积炭反应的表观活化能较高,从而抑制积炭反应的进行.1.

Carbon spices on Ni/γ-Al_2O_3 and Ni-Ce-Mn-Li/γ-Al_2O_3catalysts surface were characterized and analyzed by XPS. It was found that there are four types carbon species- carbonate, contaminate carbon,carbide carbon and inactive carbon on Ni/γ-Al_2O_3 catalysts surface, and there are two types carbon species-contaminate carbon, carbide carbon on good activity and stability Ni-Ce-Mn-Li/γ-Al_2O_3 catalysts surface. It is inactive carbon that led to deactivation. The study on carbon deposition kinetics show that the kinetic function of carbon deposition for this reaction systemis r_0=A·e-ERT·P1.1CH_4·P-0.45O_2·P-1.80O_2.The high activation energy for carbon deposition of Ni-Ce-Mn-Li/γ-Al_2O_3 catalyst is mean that carbon deposition reaction can be inhibited greatly.