This minireview discusses the use of zeolites as catalysts in all stages of lignocellulose biomass (LCB) valorization process. A summary of some synthesis and characterization methods for zeolitic materials is provided. Utilization of various active sites of zeolites is explored with the focus on Brønsted and Lewis acid sites and the importance of hierarchical structures in the processes involving bulky biobased molecules. Zeolites modified by top-down methods, specifically desilication with various basic reagents, are good candidates for applications in LCB valorization. Some novelty methods such as a dry milling for incorporating metal nanoparticles into zeolite structure are mentioned. An overview of studies utilizing zeolites in processes such as catalytic pyrolysis of LCB, acid-catalyzed hydrolysis and reactions of platform molecules (ethanol, furans, glycerol, bio-hydrocarbons, lactic acid, succinic acid, levulinic acid, sorbitol, xylitol) is discussed. Special attention is dedicated to reactions of biomass-derived alcohols and value-added chemicals produced from them, e.g., esters. The most successful industrial zeolite application—fluid catalytic cracking—is also summarized for comparison. Challenges of zeolite stability in reactions carried out in liquid water conditions, as well as possibilities of catalyst stabilization, e.g., with extra-framework aluminum, or hydrophobization of the surface, are explored.Graphical abstract
This review outlines a comprehensive methodology for the research and development of heterogeneous catalytic technologies (R&D_HeCaTe). Emphasis is placed on the fundamental interactions between reactants, solvents, and heterogeneous catalysts—specifically the roles of catalytic centers and support materials (e.g., functional groups) in modulating activation energies and stabilizing catalytic functionality. Particular attention is given to catalyst deactivation mechanisms and potential regeneration strategies. The application of molecular modeling and chemical engineering analyses, including reaction kinetics, thermal effects, and mass and heat transport phenomena, is identified as essential for R&D_HeCaTe. Reactor configuration is discussed in relation to key physicochemical parameters such as molecular diffusivity, reaction exothermicity, operating temperature and pressure, and the phase and “aggressiveness” of the reaction system. Suitable reactor types—such as suspension reactors, fixed-bed reactors, and flow microreactors—are evaluated accordingly. Economic and environmental considerations are also addressed, with a focus on the complexity of reactions, selectivity versus conversion trade-offs, catalyst disposal, and separation challenges. To illustrate the breadth and applicability of the proposed framework, representative industrial processes are discussed, including ammonia synthesis, fluid catalytic cracking, methanol production, alkyl tert-butyl ethers, and aniline.
1 June 1996 in Journal of Molecular Catalysis A: Chemical
Samples of papers artificially (2 to 60 days) and naturally (10, 45, and 56 years) aged were studied by the Py-GC/MS method to identify decomposition products. Possible reaction scenarios for cellulose degradation were developed. One of the degradation products is acetic acid, which can (auto)catalyze the cleavage of cellulose β(1→4)-glycosidic bonds of cellulose polymer chains. However, during 20 s of Py-GC/MS analysis, temperatures of up to 300 °C did not significantly increase or modify the formation of decomposition products of paper components. At 300 °C, the amount of several cellulose decomposition products increased regularly depending on the number of days of artificial aging and natural aging, demonstrated mainly by the generation of 2-furancarboxaldehyde, 5-hydroxymethylfurfural, and levoglucosan and its consecutive dehydration products. No correlation between the amount of lignin decomposition products and the time of aging was found when the pyrolysis was performed at 300 °C and 500 °C. Compounds present in the products of decomposition at 500 °C bear the imprint of the chemical composition of the sampled paper. Pyrograms taken at 300 °C using the Py-GC/MS method can give additional information on the changes in the chemical structure of paper during natural or artificial aging, mainly about the cleavage of β(1→4)-glycosidic bonds during aging.