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Carbon dioxide hydrogenation to form hydrocarbons was conducted on two iron-based catalysts, prepared according to procedures described in the literature, and on a new iron spinel catalyst. The CO2 conversion measured in a packed-bed reactor was limited to about 60% because of excessive amounts of water produced in this process. Switching to a system of three packed-bed reactors in series with interim removal of water and condensed hydrocarbons increased CO2 conversion to as much as 89%. The pure spinel catalyst displayed a significantly higher activity and selectivity than those of the other iron catalysts. This process produces a product called green feed, which is similar in composition to the product of a high-temperature, iron-based Fischer–Tropsch process from syngas. The green feed can be readily converted into renewable fuels by well-established technologies.

Rates of hydrogenation of α‐methyl styrene were measured at 40.6°C and 1 atm in a recycle, trickle‐bed reactor using a palladium/aluminum oxide catalyst. Data for different hydrogen concentrations in the gas and liquid feed streams suggested that except, at high liquid flow rates, on part of the outer surface of the catalyst the mass transfer limitation was very small, indicating a gas covered type of surface. A procedure was developed for evaluating effectiveness factors for the nonuniform boundary conditions existing when part of the particle surface is covered by gas.

Fixed-bed, catalytic reactors in which gas and liquid phases flow concurrently downward, termed trickle beds, are becoming more widely used in chemical processing, particularly in the petrochemical industry. Shah (1979) has summarized the advantages of trickle-bed reactors and mentioned some of the processes in 1975; Goto et al., 1977;Hofmann, 1978;Gianetto et al., 1978) have discussed factors affecting reactor performance.In the last few years additional experimental and theoretical studies that contribute to improved design and scaleup of trickle-bed reactors have been published. The scope of this paper is to review critically these improvements. Progress in understanding local rates of reaction is considered first. Then recent developments in reactor design are analyzed. MORDECHAY HERSKOWITZ Ben Gurion University of the NegevBeer Sheva, Israel and J. M. SMITH University of CaliforniaDavis, CA which the reactors are used. Shah's monograph and earlier reviews (Satterfield, LOCAL RATES OF REACTIONtances and the effective wetting of the particle. While mass transfer resistances are encountered in other three-phase reactors, the partial wetting of catalyst particles, which leads to more direct contact between the gas and the solid catalyst, is a unique feature of trickle-bed reactors.The rate of reaction in a single catalyst particle depends on intrinsic kinetics, intraparticle and interphase mass transfer resis-0001-1541-811-750901-$2.~.