【摘要】 分析积碳中的含镍量表明:在轻油水蒸汽转化制氢镍催化剂上,每100毫克催化剂上积碳量在10毫克以下时,碳中含镍量和积碳量成正比;在10毫克至25毫克之间时,碳中含镍量近似和积碳量的对数成正比;大于25毫克时,碳中含镍量不再随积碳量而变。消碳速度和积碳量之间也有类似的三种关系。这是由于这种催化剂上的消碳是镍催化消碳,消碳速度和碳中含镍量之间是正比关系。电镜观察和摄影证明,较快速的积碳主要呈碳丝状,这些碳丝交织成三维的网架结构。580℃以上消碳过程的速率控制步骤是通过这些碳网架孔的扩散。更多还原

【Abstract】 Investigation of the catalytic behavior of the nickel transferred to the carbon deposits has given two kinds of curves; one is a curve of nickel content in carbon versus the amount of carbon deposits, the other is a curve of the gasification rate of carbon versus the initial amount of carbon. A comparison of these two curves has shown clearly that the gasification rate of carbon deposits is almost proportional to the nickel content in carbon. As to the relationship between the nickel content in carbon and the amount of carbon deposits, there are three eases; when the amount of carbon is low, they are in linear proportion; when the amount of the carbon is high enough, they become independent of each other and when the amount of carbon is intermediate., the nickel content of carbon is proportional to the logarithm of the amount of carbon deposited. The proportionality of gasification rate to the nickel content indicates that the nickel particles in the carbon deposits have an considerable catalytic action in the gasification of carbon.The microstructure of some carbon samples on the supported nickel catalysts was examined under the scanning electron microscope. Those micrographs of carbon deposits clearly revealed that they are chiefly of filament structure, the length of carbon filaments vary widely, the longer ones became curled and interwoven into a three dimensional network. The carbon gasification Arrhenius-type plots between 480 and 700℃ exhibit two distinct temperature regions, with a changeover within a narrow range of temperature. The apparent energy of activation in the high temperature region is nearly half of that in the low temperature region. The changeover temperature of the two temperature regions on the Arrhenius-type plots increases as the amount of carbon deposits decreases. The rate determining step of gasification of carbon deposits in high temperature is region believed to be the diffusion of reactant gases in the network pores of carbon deposits.更多还原