Hierarchical zeolites combine the intrinsic catalytic properties of microporous zeolites and the enhanced access and transport of the additional meso- and/or macroporous system. These materials are the most desirable catalysts and sorbents for industry and become a highly evolving field of important current interests. In addition to the enhanced mass transfer leading to high activity, selectivity, and cycle time, another essential merit of the hierarchical structure in zeolite materials is that it can significantly improve the utilization effectiveness of zeolite materials resulting in the minimum energy, time, and raw materials consumption. Substantial progress has been made in the synthesis, characterization, and application of hierarchical zeolites. Herein, we provide an overview of recent achievements in the field, highlighting the significant progress in the past decade on the development of novel and remarkable strategies to create an additional pore system in zeolites. The most innovative synthesis approaches are reviewed according to the principle, versatility, effectiveness, and degree of reality while establishing a firm link between the preparation route and the resultant hierarchical pore quality in zeolites. Zeolites with different hierarchically porous structures, i.e., micro-mesoporous structure, micro-macroporous structure, and micro-meso-macroporous structure, are then analyzed in detail with concrete examples to illustrate their benefits and their fabrications. The significantly improved performances in catalytic, environmental, and biological applications resulting from enhanced mass transport properties are discussed through a series of representative cases. In the concluding part, we envision the emergence of "material-properties-by-quantitative and real rational design" based on the "generalized Murray's Law" that enables the predictable and controlled productions of bioinspired hierarchically structured zeolites. This Review is expected to attract important interests from catalysis, separation, environment, advanced materials, and chemical engineering fields as well as biomedicine for artificial organ and drug delivery systems.

Hierarchically Structured Zeolites: From Design to Application.

Biomass gasification converts into syngas, then into other chemicals via Fischer-Tropsch (F-T) synthesis is promising for renewable energy utilization. Although gasification is a sustainable and environmental-friendly technology for value-added utilization of biomass, tar formation is the major problem during the biomass gasification. Tar could condense on the reactor then block and foul equipment. An optimized gasifier and highly active catalyst were proved to be effective for biomass tar elimination. Furthermore, tar formation mechanism and the decomposition pathway were also important to advance the optimization of gasification reactors and catalyst design. This paper summarized the fundamentals, such as gasifier types, Ni-based catalyst, and reaction and deactivation mechanism. This review also sheds light on other excellent catalysts, effective gasifiers and mathematical models of biomass catalytic gasification, and catalyst reaction mechanisms and mathematical models are also discussed in detail. At last, the paper ends with a conclusion and prospective discussion to the latter lab and industrial-scale research.

Recent advances in syngas production from biomass catalytic gasification: A critical review on reactors, catalysts, catalytic mechanisms and mathematical models

A review on the catalytic pyrolysis of biomass for the bio-oil production with ZSM-5: Focus on structure

Catalytic fast pyrolysis (CFP) is a promising technology that can allow the conversion of biomass into transportable fuels. Despite its advantages in terms of simplicity and economic efficiency, the CFP of biomass has not been commercially applied. One of the biggest challenges is the precise design of highly effective zeolite catalysts tailored for biomass CFP, and the structure–property relationship of the zeolites in biomass pyrolysis is yet to be fully understood. Therefore, this review describes the key role of zeolites in the CFP of lignocellulosic biomass. First, a brief introduction of the chemistry of biomass pyrolysis is included to provide a basic understanding of the requirements for catalysts employed in CFP. Characteristic zeolite parameters such as porosity, acidity, and porosity–acidity interplay that can affect the biomass pyrolysis routes are summarized. Furthermore, to explore the next-generation catalysts, the catalytic behaviors of metal-loaded, hierarchical, layered, and nanosized zeolites in biomass CFP are discussed and evaluated. Unresolved issues in zeolite designing are also highlighted. Finally, perspectives on the future developments of zeolite catalysts for biomass CFP are presented.

Catalytic fast pyrolysis of lignocellulosic biomass: Critical role of zeolite catalysts

Co-pyrolysis of lignocellulosic and macroalgae biomasses for the production of biochar - A review.

Catalytic upgrading of pyrolysis vapors from lignite over mono/bimetal-loaded mesoporous HZSM-5

This paper presents a review of recent research on direct upgrading of coal/biomass volatiles into aromatics by catalytic pyrolysis and syngas by gasification with catalytic steam reforming. Coal/b...

Catalytic Conversion of Coal and Biomass Volatiles: A Review

HZSM-5 was post-treated by piperidine-assisted desilication (PAD) and metallic Co and/or Zr modification to introduce the meso-/microporous system and metal active sites to enhance the activity for catalytic fast pyrolysis (CFP) of lignite for aromatic products. CFP was conducted over parent and hierarchical HZSM-5 in a drop tube reactor at 600 °C and a gas residence time of 1.5 s. The results showed that assisted desilication with piperidine (PI) concentration of 0.3 mol/L (AT0.2–PI0.3), retained the morphology of HZSM-5, and avoided severe alkaline corrosion. This was due to the shield of the zeolite crystals from extensive dissolving of NaOH by organic amines. It not only decreased the deactivation rate of the catalyst, but also enhanced the mass transfer in the catalyst. The selectivity of light aromatics (LAs) such as benzene, toluene, ethylbenzene, xylene, and naphthalene remarkably increased to 24.9% over AT0.2–PI0.3 in comparison to the HZSM-5. In addition, introducing bimetallic Zr–Co facilitated...

Zhen Yang

Papers

Catalytic upgrading of pyrolysis vapors from lignite over mono/bimetal-loaded mesoporous HZSM-5

Catalytic Conversion of Coal and Biomass Volatiles: A Review

Enhancement of aromatic products from catalytic fast pyrolysis of lignite over hierarchical HZSM-5 by piperidine-assisted desilication

Preparation of hierarchical HZSM-5 based sulfated zirconium solid acid catalyst for catalytic upgrading of pyrolysis vapors from lignite pyrolysis

Catalytic conversion of lignite pyrolysis volatiles to light aromatics over ZSM-5: SiO2/Al2O3 ratio effects and mechanism insights