A. B. Shigarov

Use of Pd membranes in catalytic reactors for steam methane reforming for pure hydrogen production

This review analyzes publications on experimental studies and mathematical modeling in the field of development of a catalytic reformer (mainly, steam methane conversion) with a fixed catalytic bed. The specific feature of such a reformer is its integration with a Pd membrane for the purpose of producing high-purity hydrogen to power a low-temperature fuel cell battery.

Modeling of membrane reactor for steam methane reforming: From granular to structured catalysts

Different types and operating modes of a tubular membrane reactor for steam methane reforming with a production rate of 0.6 m3/h are compared using the results of mathematical modeling. It is shown that, for a cylindrical membrane, the use of a catalytic bed based on waved bands of porous nickel instead of a granular bed of a commercial catalyst (NIAP-18) can theoretically increase the yield of hydrogen by 15–18%.

Thermally Coupled Catalytic Reactor for Steam Reforming of Methane and Liquid Hydrocarbons: Experiment and Mathematical Modeling

An energy-efficient catalytic reactor for producing synthesis gas from methane and liquid hydrocarbons is proposed that is based on the coupling of an endothermic reaction (steam reforming of methane, hexane, or isooctane) and an exothermic reaction (hydrogen oxidation by atmospheric oxygen) in a single cocurrent apparatus. To describe the processes in such an apparatus, a two-dimensional two-temperature mathematical model is developed. It was revealed experimentally and by mathematical modeling that the heat- and mass-transfer coefficients of the gas flow in contact with the catalytically active wall in the exothermic reaction zone considerably affect the thermal conditions in the reactor.

Catalytic heat generating element for autonomous domestic heating systems

New heat-conducting metal porous reinforced catalysts were developed to manufacture a catalytic heat generating element (CHGE) of 25 kW power. The element was subjected to thermophysical, hydraulic and ecological testing. Local temperature and gas flow rates were determined in different places of the outer catalytic bed surface. We have estimated impact of the convective and radiant transfer in total CHGE heat generation. Dynamics of CHGE startup was studied. A prototype of the catalytic water boiler supplied with a CHGE of 25 kW power was manufactured and tested. The boiler provides below yield of toxic waste: CO 5–10 ppm, NOx traces, CH4 10–20 ppm, CO2 10 vol.%, the other gases 89.5 vol.%. CHGE is promising as a device for ecologically safe heat production for household appliances.

Phase Disequilibrium in the Course of an Exothermic Reaction Accompanied by Liquid Evaporation in a Catalytic Trickle-Bed Reactor

Abstractα-Methylstyrene hydrogenation in a fixed catalyst bed is studied experimentally and theoretically for a cocurrent downflow of the gas and liquid. Gas-phase hydrogenation on dry catalyst granules disturbs the liquid–vapor phase equilibrium. A dimensionless parameter related to the Raoult–Dalton law for a liquid–vapor mixture is suggested to characterize phase disequilibrium in the system.

Diesel fuel pre-reforming into methane-hydrogen mixtures

The pre-reforming of diesel fuel combined with subsequent steam reforming of pre-reforming products integrated with membrane separation of hydrogen is the most promising way of obtaining pure hydrogen for fuel cells. Here, we consider the first part of this problem-diesel fuel pre-reforming. The following commercial nickel-containing catalysts have been tested in the pre-reforming reaction: NIAP-18 (Ni, 15 wt %; CaO, 8 wt %; Al2O3, 74.4 wt %), NIAP-12-05 (Ni, 48 wt %; Cr2O3, 27 wt %), NIAP-07-01 (NiO, 36 wt %), NIAP-07-05 (NiO, 38 wt %; Cr2O3, 12 wt %). A number of new pre-reforming catalysts based on manganese and cobalt compounds have also been examined. The tests have been carried out at pressures of 1, 6, and 15 atm, temperatures of 470–560°C, and gas hourly space velocities of 6000–12000 h−1. The experiments have demonstrated that the nickel-containing catalysts afford a near-equilibrium product composition, while the reaction over the catalysts based on manganese and cobalt compounds yields a nonequilibrium product composition. A mathematical model has been developed for diesel fuel pre-reforming in an adiabatic reactor with a fixed catalytic bed. Model parameters ranging from process kinetics to heat and mass transfer coefficients have been estimated. The results of modeling have been compared to experimental data available from the literature. The potential of the mathematical model has been illustrated by performing calculations for adiabatic reactors with various output capacities.

Thermochemical conversion of fuels into hydrogen-containing gas using recuperative heat of internal combustion engines

The problem of the thermochemical recuperation of heat from the exhaust gases of internal combustion engines (ICEs) as a method of increasing of the efficiency of fuels has been considered. The thermodynamic analysis of thermochemical recuperation conditions was performed, and maximum efficiency conditions were determined. Catalysts for the steam conversion of oxygen-containing fuels into syngas were developed, and the Co-Mn/Al2O3 catalyst was shown to be the most promising. The model of a thermochemical heat recuperation system was developed and manufactured, and its bench tests in the conversion of alcohols were performed using the simulated exhaust gases from a heating device. Mathematical models for calculating units of the heat recuperation system were developed. A recuperation system was manufactured and tested in the ICE-free and ICE-integrated variants. Based on the test results, the equivalent fuel consumption characteristics of a recuperative ICE was revealed to decrease by 11–22% depending on its load with a decrease in the concentration of hazardous emissions by 8–12 times for CO, 2–3.5 times for CH, and 18–25 times for NOx.

Modeling of critical phenomena for liquid/vapor–gas exothermic reaction on a single catalyst pellet

Abstract Physical mechanisms are discussed and crude mathematical models with lumped parameters are developed, which explain the authors recent experimental data [4] , concerning temperature hysteresis and multiplicity phenomena for α-methylstyrene (AMS) liquid–vapor hydrogenation on a single catalyst pellet. The interplay between endothermic vaporization and exothermic vapor phase reaction is elucidated. The results of this study may help to develop more sophisticated models and theory of hot spots formation and runaway phenomena in trickle-bed reactors.

Catalytic external combustion engine

The operating regimes of a laboratory external combustion engine consisting of a catalytic heater, working cylinder, connection unit with hydroresistance, back pressure unit, and thermochemical recuperator have been studied. An experimental technique that provides an estimate of the power developed by an engine to perform mechanical work has been created. It has been shown that the efficiency can be increased by recuperating the heat of combustion products from the endothermic reaction of the steam that reforms the initial fuel, e.g., propane–butane, into syngas. The effect of the process parameters on an increase in the inner engine efficiency is analyzed. It has been shown that the maximum pressure in the working cylinder has the greatest effect on an increase in the inner efficiency.

Development of a Catalytic Heating System for External Combustion Engines

A catalytic heater design was proposed for an external combustion engine. This design is based on the partial oxidation or autothermal conversion of hydrocarbon fuel to syngas and its further oxidation with heat generation in a radial catalytic reactor integrated with a tubular heat exchanger. The theoretical analysis of operational regimes for a catalytic heater with a thermal power of 25–50 kW was performed with regard to the distribution of gas and the mathematical modeling of processes in a catalyst bed integrated with a heat exchanger, and some estimates were given for the performance of an external combustion engine. The conditions providing a uniform distribution of gas along the length of a radial reactor with suction of a reaction mixture into the catalyst bed were determined. A design of catalytic heating system elements was developed, and some layout solutions that provide a rational mutual arrangement of system components were created.