Special-purity hydrogen production from methane in a high-temperature converter–membrane apparatus system combined with a carbon monoxide conversion catalyzer

Abstract

It is shown by a computing method that a high-temperature methane converter−membrane apparatus system combined with carbon monoxide conversion catalyzer is of considerable interest from the point of attaining high technoeconomic indices of special-purity hydrogen production from methane. Of added interest is the feasibility of reducing the working temperature of the membrane apparatus down to 500-600°C, which would allow broadening of the range of membrane and constructional materials, including use of the palladium alloy V-1 extensively tested in practice.Search for ways of producing special-purity hydrogen (SPH) efficiently from natural gas consisting almost entirely of methane is a critical direction of contemporary hydrogen energy engineering and technology [1]. Of late, interest has been growing for building compact stationary and mobile high-purity gaseous hydrogen generators whose operation principle is based on combining catalytic methane conversion with membrane extraction of SPH [2, 3]. The reason for such interest is the potential for raising hydrogen yield and degree of methane conversion via shifting of chemical equilibriums (1, 2) to the right by selective removal of hydrogen from the reaction zone through a thin continuous palladium alloy membrane.Pilot-scale membrane apparatuses having a single-unit throughput of 100-1050 m 3 /h [4, 5] with highly permeable hydrogen-selective membranes from palladium-based alloys can provide for a long time (up to 10 years [4]) the required purity of hydrogen (99.9999 vol. %) producible from chemically nonreacting hydrogen-containing gas mixtures (H 2 -H 2 O, H 2 -N 2 ).The high-temperature converter−high-temperature membrane apparatus (HTC−HTMA) system (investigated earlier by mathematical modeling) with a catalyzer for methane conversion in the high-pressure chamber (HPC) of the membrane apparatus allows high-purity hydrogen production at 800°C with high technoeconomic indices [6], which is associated with more exhaustive extraction of hydrogen from methane conversion products by shifting chemical equilibriums (1, 2) to the right.

Evaluation of efficiency of special-purity hydrogen production from products of steam conversion of methane and its close homologs in high-temperature converter–membrane equipment system using methane or carbon monoxide conversion catalyst

“…A promising way of augmenting the efficiency and economy of compact stationary and mobile equipment for highpurity gaseous hydrogen production from methane is to combine membrane extraction of hydrogen with catalytic conversion of methane [2][3][4][5][6] or carbon monoxide [7,8].…”

“…The results of numerical modeling of membrane hydrogen extraction using approaches [6,8] and model representations [15] are plotted in Figs. 3-6.…”

“…For compact stationary SPH production units, as in [8], process version 2 of the HTC-ME system having carbon monoxide conversion catalyst in the HPC of ME-2 is more preferable. In this case, the HTC temperature must be maintained at the 1000°C level, which at the fixed membrane equipment temperature of 600°C and identical membrane thickness will help reduce the membrane area.…”

Determination of efficiency of special-purity hydrogen production from products of methane conversion with oxygen in membrane apparatus in combination with catalytic methane or carbon monoxide conversion

“…One of the promising ways of augmenting the efficiency and economic viability of compact stationary and mobile gaseous special-purity hydrogen producing units is combining membrane extraction of hydrogen with catalytic conversion (reforming) of methane [5][6][7][8] or carbon monoxide [9,10]. In this process, hydrogen yield rises on account of shifting of the chemical equilibriums in the presence of a methane or a carbon monoxide conversion catalyst in the high-pressure chamber (HPC) of the membrane apparatus (MA) upon selective extraction of hydrogen from the gaseous phase through a thin continuous membrane from palladium alloys.…”

“…The results of numerical modeling of the test HTC-MA system within the confines of the approaches [7,8,10] and the model representations [15] are adduced in Table 1.…”