Abatement of various types of VOCs by adsorption/catalytic oxidation: A review

Propylene is an important building block for enormous petrochemicals including polypropylene, propylene oxide, acrylonitrile and so forth. Propane dehydrogenation (PDH) is an industrial technology for direct propylene production which has received extensive attention in recent years. With the development of dehydrogenation technologies, the efficient adsorption/activation of propane and subsequential desorption of propylene on the surfaces of heterogeneous catalysts remain scientifically challenging. This review describes recent advances in the fundamental understandings of the PDH process in terms of emerging technologies, catalyst development and new chemistry in regulating the catalyst structures and inhibiting the catalyst deactivation. The active sites, reaction pathways and deactivation mechanisms of PDH over metals and metal oxides as well as their dependent factors are also analysed and discussed, which is expected to enable efficient catalyst design for minimizing the reaction barriers and controlling the selectivity towards propylene. The challenges and perspectives of PDH over heterogeneous catalysts are also proposed for further development.

Propane dehydrogenation: catalyst development, new chemistry, and emerging technologies

In this study, Ag deposited three-dimensional MnO2 porous hollow microspheres (Ag/MnO2 PHMSs) with high dispersion of the atom level Ag species are first prepared by a novel method of redox precipitation. Due to the highly efficient utilization of downsized Ag nanoparticles, the optimal 0.3% Ag/MnO2 PHMSs can completely degrade 70 ppm CH3SH within 600 s, much higher than that of MnO2 PHMSs (79%). Additionally, the catalyst retains long-term stability and can be regenerated to its initial activity through regeneration with ethanol and HCl. The results of characterization of Ag/MnO2 PHMSs and catalytic performance tests clearly demonstrate that the proper amount of Ag incorporation not only facilitates the chemi-adsorption but also induces more formation of vacancy oxygen (Ov) and lattice oxygen (OL) in MnO2 as well as Ag species as activation sites to collectively favor the catalytic ozonation of CH3SH. Ag/MnO2 PHMSs can efficiently transform CH3SH into CH3SAg/CH3S-SCH3 and then oxidize them into SO42– and...

Enhanced Performance and Conversion Pathway for Catalytic Ozonation of Methyl Mercaptan on Single-Atom Ag Deposited Three-Dimensional Ordered Mesoporous MnO2.

Catalytic non-oxidative direct dehydrogenation of light alkanes serves as an effective reinforcement to selectively produce the corresponding olefins, and the heterogeneous metals and metal oxides, not limited to the commercially used Pt- and Cr-based catalysts, are widely investigated to enhance the efficiency. In this review, we outline the progress of these dehydrogenation catalysts that have been mainly developed in the past five years. For different classes of the most-promising catalysts in the selective dehydrogenation of ethane-to-ethylene and propane-to-propylene, their syntheses, structural information, catalytic properties and mechanisms are comparatively summarized.

Recent progress in heterogeneous metal and metal oxide catalysts for direct dehydrogenation of ethane and propane

Conversion of propane or butanes from natural/shale gas into propene or butenes, which are indispensable for the synthesis of commodity chemicals, is an important environmentally friendly alternative to oil-based cracking processes. Herein, we critically analyse recent developments in the non-oxidative, oxidative, and CO2-mediated dehydrogenation of propane and isobutane to the corresponding olefins over metal oxide catalysts. Particular attention is paid to (i) comparing the developed catalysts in terms of their application potential, (ii) structure-activity-selectivity relationships for tailored catalyst design, and (iii) reaction-engineering aspects for improving product selectivity and overall process efficiency. On this basis, possible directions for further research aimed at the development of inexpensive and environmentally friendly catalysts with industrially relevant performance were identified. In addition, we provide general information regarding catalyst preparation and characterization as well as some recommendations for carrying out non-oxidative and CO2-mediated dehydrogenation reactions to ensure unambiguous comparison of catalysts developed in different studies.

Current status and perspectives in oxidative, non-oxidative and CO2-mediated dehydrogenation of propane and isobutane over metal oxide catalysts.

Enhancement of catalytic performance and resistance to carbonaceous deposit of lanthanum (La) doped HZSM-5 catalysts for decomposition of methyl mercaptan

Cr‐modified MCM‐41 with different loadings were prepared and tested in the propane dehydrogenation (PDH) reaction. As for Cr/MCM‐41 system, the general knowledge was that high Cr loadings resulted in the reduction of silica surface hydroxyl groups, thus leading to the formation of inactive Cr(III) species, as clusters and/or crystalline Cr2O3. However, in the present work, isolated Cr(VI) states were identified in the Cr/MCM‐41 catalysts, instead of Cr(III) species, using UV‐vis and H2‐TPR. These isolated Cr(VI) species are difficult to reduce, causing the decreased activity for propane conversion and low selectivity towards C3H6 in the PDH process. In contrast, a good dispersion of the Cr species was obtained using a chromium column adsorption process, and the absence of the isolated state of Cr(VI) species on this sample contributed to high activity toward PDH process. The investigation of the isolated Cr(VI) species is very important for the Cr‐based PDH catalyst system.

Investigation of the Isolated Cr(VI) Species in Cr/MCM‐41 Catalysts and its Effect on Catalytic Activity for Dehydrogenation of Propane

The Cr/Al2O3 catalyst is a typical commercial catalyst system that has been widely applied for propane dehydrogenation (PDH). Appreciable improvement in catalytic performance of this catalyst is of...

Effect of a Ce Promoter on Nonoxidative Dehydrogenation of Propane over the Commercial Cr/Al2O3 Catalyst

Recycling waste Cr adsorbents as efficient catalysts reflects a new avenue of green chemistry and has important implications for environmental protection. In particular, the investigation of the ef...

Shuang Yang

Papers

Enhancement of catalytic performance and resistance to carbonaceous deposit of lanthanum (La) doped HZSM-5 catalysts for decomposition of methyl mercaptan

Investigation of the Isolated Cr(VI) Species in Cr/MCM‐41 Catalysts and its Effect on Catalytic Activity for Dehydrogenation of Propane

Effect of a Ce Promoter on Nonoxidative Dehydrogenation of Propane over the Commercial Cr/Al2O3 Catalyst

Development of a Strategy To Reuse Spent Cr Adsorbents as Efficient Catalysts: From the Perspective of Practical Application

The effects of Cr addition in HZSM-5 on its structure, physicochemical and catalytic properties for methyl mercaptan abatement