Tar formation is one of the major problems to deal with during biomass gasification. Tar condenses at reduced temperature, thus blocking and fouling process equipments such as engines and turbines. Considerable efforts have been directed on tar removal from fuel gas. Tar removal technologies can broadly be divided into two approaches; hot gas cleaning after the gasifier (secondary methods), and treatments inside the gasifier (primary methods). Although secondary methods are proven to be effective, treatments inside the gasifier are gaining much attention as these may eliminate the need for downstream cleanup. In primary treatment, the gasifier is optimized to produce a fuel gas with minimum tar concentration. The different approaches of primary treatment are (a) proper selection of operating parameters, (b) use of bed additive/catalyst, and (c) gasifier modifications. The operating parameters such as temperature, gasifying agent, equivalence ratio, residence time, etc. play an important role in formation and decomposition of tar. There is a potential of using some active bed additives such as dolomite, olivine, char, etc. inside the gasifier. Ni-based catalyst are reported to be very effective not only for tar reduction, but also for decreasing the amount of nitrogenous compounds such as ammonia. Also, reactor modification can improve the quality of the product gas. The concepts of two-stage gasification and secondary air injection in the gasifier are of prime importance. Some aspects of primary methods and the research and development in this area are reviewed and cited in the present paper.

A review of the primary measures for tar elimination in biomass gasification processes

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.

Catalytic dehydrogenation of light alkanes on metals and metal oxides.

This book offers comprehensive coverage of the design, analysis, and operational aspects of biomass gasification, the key technology enabling the production of biofuels from all viable sources--some examples being sugar cane and switchgrass. This versatile resource not only explains the basic principles of energy conversion systems, but also provides valuable insight into the design of biomass gasifiers. The author provides many worked out design problems, step-by-step design procedures and real data on commercially operating systems. After fossil fuels, biomass is the most widely used fuel in the world. Biomass resources show a considerable potential in the long term if residues are properly handled and dedicated energy crops are grown. 5 years of the author's research in the area Biomass fuel production First book devoted to Biomass Gasification Includes step-by-design procedures, cases studies and worked out numerical examples

Biomass Gasification and Pyrolysis: Practical Design and Theory

It is well known that urbanization and industrialization have resulted in the rapidly increasing emissions of volatile organic compounds (VOCs), which are a major contributor to the formation of secondary pollutants (e.g., tropospheric ozone, PAN (peroxyacetyl nitrate), and secondary organic aerosols) and photochemical smog. The emission of these pollutants has led to a large decline in air quality in numerous regions around the world, which has ultimately led to concerns regarding their impact on human health and general well-being. Catalytic oxidation is regarded as one of the most promising strategies for VOC removal from industrial waste streams. This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades. It addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions. It also highlights the primary routes for catalyst deactivation and discusses protocols for their subsequent reactivation. Kinetic models and proposed oxidation mechanisms for representative VOCs are also provided. Typical catalytic reactors and oxidizers for industrial VOC destruction are further discussed. We believe that this Review will provide a great foundation and reference point for future design and development in this field.

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Recent Advances in the Catalytic Oxidation of Volatile Organic Compounds: A Review Based on Pollutant Sorts and Sources.

Catalytic oxidation of volatile organic compounds (VOCs) – A review

The preparation of catalysts suitable for MTG processes in a fluidized bed reactor has been studied with emphasis on improving the textural, physico-chemical, morphological, structural and mechanical properties. A mixture of HZSM-5 zeolite (active material), boehmite or bentonite (binder) and alumina (inert filler) was used to prepare different catalysts. After preparation, characterization by physical adsorption of N2, XRF, XRD and SEM-EDX techniques was carried out. The screening of catalysts was performed in a fluidized bed reactor. The distribution of products was very similar in all cases, with the yield of light hydrocarbons always being higher than that of gasoline. Among the catalysts tested, the one containing boehmite as a binder (HZ_Boeh) was found as the most appropriate due to its high mechanical strength, high yield to aromatics and lower yield to durene.

https://www.mdpi.com/2073-4344/12/2/134/pdf?version=1645524571

Methanol to Gasoline (MTG): Preparation, Characterization and Testing of HZSM-5 Zeolite-Based Catalysts to Be Used in a Fluidized Bed Reactor

Methanol-to-olefins is a promising process that has attracted the attention of many research groups in the last years. Zeolites are the primary catalyst for this process, and SAPO-34 is one of the ...

https://pubs.acs.org/doi/pdf/10.1021/acs.iecr.1c02718

MTO with SAPO-34 in a Fixed-Bed Reactor: Deactivation Profiles

Publisher Summary The deactivation of catalysts by coke deposition and its subsequent regeneration poses one of the most important problems in industrial catalytic processes. Supported and coprecipitated nickel catalyst represent an interesting alternative, from the economical point of view, to other selective hydrogenation catalysts such as Pt or Pd, of higher performance but also with a higher price. This chapter uses a coprecipitated NiO/NiAl 2 O 4 catalyst to carry out the selective hydrogenation of acetylene to ethylene as a test reaction. One important characteristic of this process is the large amount of coke that may be generated. The crystalline structure of the catalyst and the oxidation state of surface nickel are especially relevant in this case because coke deposition as well as acetylene hydrogenation occur on the metallic nickel sites. Therefore, the pretreatments carried out on the catalyst with the aim of obtaining the active species have a great influence on the relationship between coke deposition and the main reaction kinetics. The chapter underlines the importance of the pretreatment temperature on the kinetic behavior of the catalyst and indicates that the pretreatment conditions should be carefully optimized in this process. The physicochemical characterization has been carried out by XPS and TPR, and the variation of the surface properties has been related to the observed hydrogenation and coke formation kinetics.

Influence of the catalyst pretreatment on the relative rates of the main and coking reactions during acetylene hydrogenation on a NiO/NiAl2O4 catalyst

Methane aromatization is a promising technology for the transformation of natural gas to liquid products, but suffers the problem of catalyst deactivation by coke. A Two-zone fluidized bed reactor has been proposed as a tool to counteract the catalyst deactivation, by providing continuous catalyst regeneration in the same vessel where the main reaction is carried out. This work shows the effect of the main operating conditions (carburization temperature, reaction temperature, carburization time, nature of regenerating agent and feed flow and height of the hydrocarbon entry point) .

/pdf/methane-aromatization-in-a-fluidized-bed-reactor-parametric-i5bip1ggwk.pdf

Methane Aromatization in a Fluidized Bed Reactor: Parametric Study

Methanol can be obtained through CO2 hydrogenation in a membrane reactor with higher yield or lower pressure than in a conventional packed bed reactor. In this study, we explore a new kind of membrane with the potential suitability for such membrane reactors. Silicone–ceramic composite membranes are synthetized and characterized for their capability to selectively remove water from a mixture containing hydrogen, CO2, and water at temperatures typical for methanol synthesis. We show that this membrane can achieve selective permeation of water under such harsh conditions, and thus is an alternative candidate for use in membrane reactors for processes where water is one of the products and the yield is limited by thermodynamic equilibrium.

https://www.mdpi.com/2077-0375/11/7/472/pdf

Javier Herguido

Papers

Methanol to Gasoline (MTG): Preparation, Characterization and Testing of HZSM-5 Zeolite-Based Catalysts to Be Used in a Fluidized Bed Reactor

MTO with SAPO-34 in a Fixed-Bed Reactor: Deactivation Profiles

Influence of the catalyst pretreatment on the relative rates of the main and coking reactions during acetylene hydrogenation on a NiO/NiAl2O4 catalyst

Methane Aromatization in a Fluidized Bed Reactor: Parametric Study

Polymer–Ceramic Composite Membranes for Water Removal in Membrane Reactors