Nanoporous Zeolite-A Sheltered Pd-Hollow Fiber Catalytic Membrane Reactor for Propane Dehydrogenation

Abstract

Pd-based membranes are used for separation of H 2 from different feed stocks; however, their application is limited in the presence of hydrocarbons due to coke deposition on the membrane surface under operation conditions. Herein, we have developed a triple-layered membrane with a nanoporous Linde type A zeolite on the outer side and an ultrathin (1 μm) Pd membrane on the inner side of the Al 2 O 3 hollow fiber substrate. The membrane was successfully synthesized and tested for hydrogen separation in the presence of lighter hydrocarbons. The presence of uniform nanosize pores in the zeolite layer acts as a barrier for the hydrocarbons to come in contact with the Pd membrane and selectively allows H 2 to permeate through the membrane. The membrane showed enhanced performance in the presence of lighter hydrocarbons (C 3 H 8 and C 3 H 6 ) compared to the only internal coated Pd membrane. The membrane showed excellent stability in the presence of propane and propene at 600 °C for 72 h of operation. The triple-layered membrane was used for propane dehydrogenation reaction using 7.5 wt % Cr/Al 2 O 3 catalyst at 600 °C, and the catalytic activity and stability of the catalytic membrane reactor were evaluated. The results revealed a propane conversion in the membrane reactor ∼15% higher than that in the conventional fixed bed catalytic reactor, which is attributed to the continuous removal of hydrogen from the product mixture during the course of the reaction.

Oxidative Dehydrogenation of Propane to Propylene with Soft Oxidants via Heterogeneous Catalysis

“…Chemical looping offers opportunities for process intensification and energy loss minimization, which is of significance in future commercialization . Current progress focuses on the feasibility of O 2 -assisted dehydrogenation of light alkanes. , Membrane reactors are emerging as an active research direction in light alkane conversion, such as propane dehydrogenation , and methane conversion, because it enables the process intensification by integrating oxidant permeability and catalytic activity in one unit . In ODHP, this novel reactor can achieve a uniform distribution of oxidant, thereby resulting in inhibited overoxidation and enhanced C 3 H 6 selectivity.…”

PtZn intermetallic nanoalloy encapsulated in silicalite‐1 for propane dehydrogenation

“…Propylene is one of the most important feedstocks in the global economy for the production of various chemicals and fuels 1–4 . The worldwide increasing demand of propylene together with the increasing availability of propane from clean energy source as shale gas has spurred interest in on‐purpose production of propylene via direct dehydrogenation 5–9 . Pt‐based catalysts are widely used in industrial propane dehydrogenation (PDH) processes because of their superior activation of paraffinic CH bonds and low activity to CC cleavage 10–12 .…”

Sintering of the Metallic Nickel Hollow Fibers into High-Performance Membranes for H2 Permeation

“…Inert ceramic porous supports exhibited more chemical stability but still suffered from the peeling-off problem due to the different thermal expansion coefficients between ceramics and metals. Even though coating the Pd layer on the inner surface of ceramic porous tubes can relieve the peeling-off problem, it is still not enough for industrial applications. ,− Additionally, poor chemical stability in the presence of a trace amount of CO or hydrocarbons limits the widespread applications of Pd-based membranes. − Adding an additional zeolite layer can prevent the Pd membrane from coking by hydrocarbon cracking but at the same time significantly increase mass transfer resistance for H 2 permeation and the overall cost …”