Partial Oxidation of Residual Oils with Air and Steam in the Fluidized Bed of Nickel-Dolomite Catalyst

Abstract

Partial oxidation of residual oils with air and steam has been investigated using a fluidized bed of a nickel-dolomite catalyst for the purpose of produing fuel gas. When nickel is supported on dolomite which absorbs H₂S, the partial pressure of H₂S at gasification is kept at so low concentration that poisoning of the nickel active sites can be avoided. In the presence of the nickel-dolomite catalyst, partial oxidation by air converted residual oils mostly to carbon monoxide and hydrogen with minor production of methane or ethylene. The yield of product gas, however, increased by the addition of steam as a gasifing agent instead of air alone. The optimum ratio of steam to air was found when 25% of necessary oxygen atom were supplied from steam (Fig. 2). Arabian Light topped residue was gasified almost competely and the product gas composition was nearly at equilibrium at 900°C (Table 3). Simultaneously, 98% sulfur in the feed oil was absorbed by calcium oxide in the catalyst support (Fig. 3). By the addition of steam to air, durability of gasification activity and desulfurization ability of the catalyst was impoved from 20 to 25%, and 40 to 55% of calcium utilization, respectively (Figs. 5, 6). The reactivity of topped and vacuum other than Arabian Light topped residue was studied at various ratios of steam to air at 900°C. The reactivity decreased with increasing amount of Conradson Carbon Residue in the feed oil (Fig. 7). The general pattern in gasification and desulfurization showed no change with a change of the feed oil (Table 4, Fig. 8).