Residual oil cracking combined with hydrogen production by steam‐iron reaction

Abstract

A new residual oil upgrading process has been developed. Residual oils were cracked over an iron oxide catalyst with simultaneous generation of hydrogen. The newly‐developed iron oxide catalyst containing CaO and Cr2O3 was found to be a good catalyst for this process because it exhibited stable activity in the steam‐iron reaction in the laboratory experiment and also in a large scale pilot plant. Effects of these foreign oxides on redox cycles were investigated. The catalyst was designed so as to maintain the stoichiometric balance between the reduction of magnetite and the oxidation of wustite by adding CaO and Cr2O3.

Steam Reforming of Woody Biomass in a Fluidized Bed of Iron Oxide-Impregnated Porous Alumina

“…There are many possible reaction pathways, including the following: (1) devolatilization, (2) steam reforming of char, (3) reforming of tar in the gas phase, (4) reforming or cracking of coke on the alumina, (5) reforming or cracking of coke on the iron oxide, (6) the water-gas shift reaction (WGSR) on the active site of the char surface, 12 (7) reforming of char by contact with the iron oxide, and (8) the steam-iron reaction. [13][14][15] The steam reforming of char (path 2) and the WGSR on char (path 6) can be eliminated by using a two-stage fluidized bed reactor, because in this reactor steam can come into contact with the coke on the Fe-impregnated alumina, but not with the char. In the single-stage reactor, char is gradually accumulated in the bed and then steam reforming is promoted by contact between the iron oxide and the char (path 7).…”

“…The iron oxide played an important role in H 2 formation during steam reforming, but it is difficult to determine the H 2 formation pathway during steam reforming on Fe-impregnated alumina. There are many possible reaction pathways, including the following: (1) devolatilization, (2) steam reforming of char, (3) reforming of tar in the gas phase, (4) reforming or cracking of coke on the alumina, (5) reforming or cracking of coke on the iron oxide, (6) the water−gas shift reaction (WGSR) on the active site of the char surface, (7) reforming of char by contact with the iron oxide, and (8) the steam−iron reaction. − …”

“…The steam-iron reaction has been reported as a possible method for H 2 production: [13][14][15] Furthermore, lattice oxygen in metal oxides can be utilized to reform hydrocarbons. 16 In the case of iron oxide, the stoichiometric equation can be expressed as follows:…”

“…The steam−iron reaction has been reported as a possible method for H 2 production: − Furthermore, lattice oxygen in metal oxides can be utilized to reform hydrocarbons . In the case of iron oxide, the stoichiometric equation can be expressed as follows: On the basis of these literature reports, we expected that if porous alumina impregnated with iron oxide were used as a bed material for the steam reforming of woody biomass in a fluidized bed, tar could be captured on the alumina and then reformed to produce H 2 by a combination of the reactions shown in eqs 1 and 2.…”

Effects of Ca-Based Catalysts on Biomass Gasification with Steam in a Circulating Spout-Fluid Bed Reactor

“…According to Table 2, it is found that both CL and CD contain some Fe 2 O 3 . By the acts of iron oxide, the quality of H 2 -rich gas may be further upgraded as the following reaction paths: [20][21][22] Fe From reactions 1-4, iron oxide enhances the water-gas shift reaction and the reforming reactions of tar and light hydrocarbon (C n H m ), which all contribute to the increment of H 2 yield. For the Ca-based catalyst, active ingredient CaO displays better catalytic selectivity for the reactions of tar and carbon but a poor role in the reforming reaction of light hydrocarbon and the water-gas shift reaction.…”