Comparing mono- and bimetallic noble-metal catalysts in a catalytic membrane reactor for methylcyclohexane dehydrogenation
- Swiss Federal Inst. of Technology, Zuerich (Switzerland). Chemical Engineering Dept.
H{sub 2} storage, in the form of liquid organic hydrides, e.g., methylcyclohexane (MCH), was proposed for the seasonal storage of electricity. A catalytic membrane reactor (CMR) containing a catalyst bed and a tubular palladium-silver (Pd-Ag) membrane to separate the coproduced H{sub 2}, was used to obtain higher than equilibrium conversions in the dehydrogenation of methylcyclohexane (MCH). A monometallic, Pt/Al{sub 2}O{sub 3} (MM30S), and a bimetallic, Pt-Re/Al{sub 2}O{sub 3} (BM30), noble-metal catalysts and two membranes with 0.1 and 0.2 mm wall thickness were employed. Experiments in the CMR at 573--673 K, 1--2 MPa, and liquid hourly space velocities (LHSVs) up to 12 volume feed/(h{times}reactor volume) showed that catalyst MM30S was outstanding in performance giving significant improvement in toluene (TOL) and H{sub 2} yields over the equilibrium values at commercially relevant conditions. Catalyst BM30 deactivated exceeding equilibrium yields to extents considerably lower than those with catalyst MM30S. However, the ratios of H{sub 2} permeation to generation rates were almost equal for the two catalysts under comparable conditions. The extent by which the equilibrium conversions were exceeded, decreased as the LHSV increased due to permeation limited operation. Reactor axial temperature profiles showed the existence of two cold spots in the CMR. An attempt is made to correlate the extent of MCH conversion to TOL in the CMR with the operating variables.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 63293
- Journal Information:
- Industrial and Engineering Chemistry Research, Vol. 34, Issue 3; Other Information: PBD: Mar 1995
- Country of Publication:
- United States
- Language:
- English
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