Catalytic reforming of lignite pyrolysis volatiles over sulfated HZSM-5: Significance of the introduced extra-framework Al species

ACS Sustainable Chem. Eng.

Yao

et al. 2021

Self Cite

Catalytic re-forming of lignite pyrolysis volatiles to aromatics over zeolites is a promising method for value-added utilization of coal tar. However, to achieve a significant enhancement in both the yields of light aromatics and the catalytic lifetime by adjusting the structure of ZSM-5 zeolite and to understand its catalytic mechanism comprehensively are still great challenges. Herein, a self-assembled hierarchical core−shell ZSM-5@silicalite-1 with controlled mesopores and acidity as well as an ultrathin nonacidic protective shell was synthesized through a mild hydrothermal method of alkaline treatment with tetrapropylammonium hydroxide or tetraethylammonium hydroxide (TPAOH or TEAOH). Both the number and pore size distribution of mesopores can be regulated by adjusting the hydrothermal treatment time. These generated mesopores not only facilitate the mass transfer of reactants and products but also improve the utilization efficiency of the acid site. In addition, the newly fabricated nonacidic shell, which coats on the surface of ZSM-5 as a chain mail, plays a critical role in suppressing the coke formation by passivation of the acid sites on the external surface. In this work, the pore properties and acid distribution of ZSM-5 zeolite can be regulated synchronously through a desilication−recrystallization process. In addition, enhanced yields of light aromatics and catalytic lifetime were obtained simultaneously. The construction of this hierarchical core−shell zeolite with redistributed acid sites contributes to the highly efficient catalytic upgrading of macromolecular reactants.

“…It was sieved to a 40–60 mesh and then dried at 107 °C for 24 h to remove the physically adsorbed water. The basic properties of SL have been described in one of our previous works …”

Section: Experimental Sectionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Simultaneous Enhancement of Aromatic Products and Catalytic Lifetime for Catalytic Re-forming of Lignite Pyrolysis Volatiles over a Self-Assembled Hierarchical Core–Shell ZSM-5@Silicalite-1 Zeolite

Feng

ACS Sustainable Chem. Eng.

Yao

et al. 2021

Self Cite

“…They observed that bimetallic Ni-Fe/Al 2 O 3 with the optimum composition of Fe/Ni = 0.5 exhibited higher catalytic activity than monometallic Ni/Al 2 O 3 and Fe/Al 2 O 3 catalysts. In recent years, zeolites with different pore sizes and active sites were already proved to be effective in tar cracking into aromatic hydrocarbons and syngas after metal addition. − Chen et al employed Ni/HZSM-5 with 6 wt % Ni loading for tar reforming in a fixed-bed reactor and investigated the effects of reaction conditions on catalyst activity. They reported that tar conversion reached 91.5% when the reaction temperature and weight hourly space velocity were 500 °C and 0.65 h –1 , respectively.…”

Section: Heterogeneous Catalysts and Catalytic Mechanismsmentioning

confidence: 99%

Understandings of Catalyst Deactivation and Regeneration during Biomass Tar Reforming: A Crucial Review

Ren

ACS Sustainable Chem. Eng.

Yang

et al. 2021

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Value-added chemicals originating from biomass gasification in the presence of advanced catalysts have proved to be promising for valuable chemical generation via deep processing. In the issues of biomass gasification, the deactivation of heterogeneous catalysts is a common problem during the reforming of biomass tar and derived model compounds. Herein, deactivation pathways and regeneration methods are crucial to understand the production of value-added chemicals and guide the design of heterogeneous catalysts during biomass gasification. Unfortunately, to the best of our knowledge, there still has been no review to conclude the recent advances in catalyst deactivation and regeneration. To address the issues mentioned above, in this perspective, common catalysts for biomass tar reforming are first discussed. Then, key features and considerations of catalyst deactivation especially catalyst poisoning and carbon deposition are comprehensively reviewed based on the latest literature reports. Finally, the possible methods of tar elimination, metallic site recovery, and catalyst optimization are reviewed. Meanwhile, the future perspectives toward catalyst design, deactivation, and regeneration in tar reforming are shared. Through this perspective, the existing challenges, solutions, and future strategies in tar reforming or other gas−solid reactions are expected to be made clearer for following research on practical applications on an industrial scale.

“…Moreover, excess SS is becoming a thorny issue faced by human beings. , Conventional SS treatment methods (such as incineration and land application) are difficult to achieve the both goals of SS reduction and recovery of organic components. Pyrolysis is one of the thermal processing technologies applied to convert organic matter in biomass into gas, solid products, and bio-oil in the absence of oxygen. − Recently, SS pyrolysis investigations conducted on variety of reactors and the product composition were studied. , Due to the poor quality of bio-oil (such as high contents of oxygen and nitrogen) gained from pyrolysis process, catalytic fast pyrolysis (CFP) of SS was investigated to utilize catalysts to reform the pyrolysis vapors …”

Section: Introductionmentioning

confidence: 99%

Catalytic Fast Pyrolysis of Sewage Sludge over HZSM-5: A Study of Light Aromatics, Coke, and Nitrogen Migration under Different Atmospheres

Shan

et al. 2020

Ind. Eng. Chem. Res.

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Catalytic fast pyrolysis of sewage sludge was conducted considering the effects of pyrolysis temperature, atmospheres and catalysts on carbon and nitrogen distributions using a fixed-bed reactor. H2 atmosphere gave the lowest carbon selectivity of solid products and highest gaseous products yield over HZSM-5 (HZ) at the same temperature compared to Ar and steam. Higher temperature led to an increase in the carbon selectivity of gaseous products and a decrease in the carbon selectivity of solids. H2 increased the carbon yield of light aromatics (LAs), whereas steam reduced the generation of LAs. Over 0.5Ni-HZ, H2 gave the highest LAs carbon yield of 11.4%, compared to 1.6% obtained from noncatalytic fast pyrolysis of SS. Higher temperature, H2 and steam atmospheres, and metal-loaded HZ promoted the transfer of nitrogen into gaseous products. The highest nitrogen yield of NH3 of 55.6% was obtained from sludge pyrolysis over HZ at 700 °C under H2 atmosphere.