Membrane reactors for hydrogenation and dehydrogenation processes based on supported palladium
TL;DR: In this article, the authors discuss two different membrane reactor concepts which both rely on supported palladium, on the one hand as a permselective membrane material, and on the other hand as base component of a membrane-type hydrogenation catalyst.
Abstract: Membrane reactors applied to catalytic reactions are currently being studied in many places world-wide. Significant developments in membrane science and the vision of process intensification by multifunctional reactors have stimulated a lot of academic and industrial research, which is impressively demonstrated by more than 100 scientific papers on catalytic membrane reactors being published per year. Palladium as a noble metal with exceptional hydrogen permeation properties and, at the same time, broad applicability as a catalyst, first of all for hydrogenation, is part of many of these developments. This paper discusses two different membrane reactor concepts which both rely on supported palladium, on the one hand as a permselective membrane material, and on the other hand as base component of a membrane-type hydrogenation catalyst. Dense palladium composite membranes can be used for hydrogen separation from packed-bed catalysts in gas-phase hydrocarbon dehydrogenation reactions. Mesoporous membranes containing dispersed bimetallic Pd/X-clusters can be employed as so-called catalytic diffusers for liquid-phase hydrogenation, e.g. of nitrate and nitrite in water. The principles of both concepts are introduced, recently obtained experimental data are evaluated in connection with literature results, and the perspectives for further development are highlighted.
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TL;DR: The study compares different catalysts in terms of the reaction mechanism and deactivation pathways and catalytic performance, as dehydrogenation for the production of light olefins has become extremely relevant.
Abstract: A study is conducted to demonstrate catalytic dehydrogenation of light alkanes on metals and metal oxides. The study provides a complete overview of the materials used to catalyze this reaction, as dehydrogenation for the production of light olefins has become extremely relevant. Relevant factors, such as the specific nature of the active sites, as well as the effect of support, promoters, and reaction feed on catalyst performance and lifetime, are discussed for each catalytic Material. The study compares different catalysts in terms of the reaction mechanism and deactivation pathways and catalytic performance. The duration of the dehydrogenation step depends on the heat content of the catalyst bed, which decreases rapidly due to the endothermic nature of the reaction. Part of the heat required for the reaction is introduced to the reactors by preheating the reaction feed, additional heat being provided by adjacent reactors that are regenerating the coked catalysts.
1,306 citations
TL;DR: The aim of this review is to highlight recent advances in hydrogen selective membranes along with the advances for the different types of membrane reactors available (from packed bed to fluidized bed, from micro-reactors to bio-membrane reactors).
564 citations
TL;DR: In this article, a review describes palladium and palladium alloy membranes for hydrogen separation prepared by different fabrication methods and using different membrane supports, and several correlations of structure and function for those membranes are provided based on mechanistic considerations of permeance along with structural properties and membrane morphologies.
539 citations
TL;DR: The integration of reaction and separation in catalytic membrane reactors has received increasing attention during the past 30 years as discussed by the authors, with the advent of new inorganic materials and processing techniques, there has been renewed interest in exploiting the benefits of membranes in many industrial applications.
438 citations
TL;DR: In this article, a survey of high-temperature membranes and several possible applications of membrane reactors for integration in power generation cycles with CO2 capture is presented and discussed, and the current performance and limitations of relevant inorganic membranes are presented, as well as further development and validation of performance of membranes in real applications are needed.
Abstract: A survey is made of high-temperature membranes and several possible applications of membrane reactors for integration in power generation cycles with CO2 capture. Current performance and limitations of relevant inorganic membranes are presented and discussed. Integrated H2, O2 or CO2 membrane separation is analysed and it is concluded that development of power plant concepts including membrane technology is not yet fully explored. Significant design optimisation would be required in order to identify efficient, feasible and environmentally sound technical solutions. In addition, further development and validation of performance of membranes in real applications are needed.
396 citations
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TL;DR: In this paper, an extensive review of the literature dealing with the class of catalytic membrane reactors which involves hydrogen permeable membranes made of palladium and palladium alloys is presented.
Abstract: This paper is an extensive review of the literature dealing with the class of catalytic membrane reactors which involves hydrogen permeable membranes made of palladium and palladium alloys. The fundamental factors which affect hydrogen permeability are first discussed. A classification of the many reactions which have been conducted in such reactors at both laboratory and commercial scales is then presented. The various techniques for the preparation of palladium- based membranes are described and the literature on modeling and design of these reactors is also reviewed.
651 citations
02 Nov 2005
TL;DR: The present and the future of structured catalysts is discussed in this article, where the authors present a review of the past, present and future monolithic catalysts for the selective reduction of NOx with NH3 from stationary monolith reactors.
Abstract: The present and the future of structured catalysts - an overview. Reactors with structured catalysts where no convective mass transfer over a cross section of the reactor occurs (monolithic catalysts = honeycomb catalysts): ceramic catalyst supports for casoline fuel metal and coated-metal catalysts autocatalysts - past, present and future monolithic catalysts for the selective reduction of NOx with NH3 from stationary monolith reactors unconventional utilization of monolithic
523 citations
TL;DR: In this paper, the authors give an overview of the advanced technologies currently used for abating emissions from the gasoline and diesel internal combustion engines. And the challenges towards the end of the 20th century into the 21st century are discussed.
385 citations
TL;DR: In this paper, a supported palladium catalyst was proposed to reduce nitrate and nitrite to nitrogen with a selectivity of 99.9% using hydrogen on noble metal catalysts.
337 citations