Effect of using regenerated combined FAU and MOR zeolites as catalysts during the pyrolysis of kraft lignin

Abstract

The SiO2/Al2O3 mole ratio, pore size, and acid sites are the key parameters of zeolite’s activity in lignin pyrolysis. In this study, the comparison of individual Y and M zeolites, the combined ‘Y + M’ sample after regeneration, and their effect on lignin pyrolysis were studied in five cycles (regeneration and reuse). The results were explained using Brunauer, Emmet, and Teller (BET), micropore surface area (MSA), and total acid sites (TAS) analyses. In comparison with the individual Y or M zeolite sample, the consistent higher catalytic activities of the combined ‘Y + M’ sample in repeated cycles were observed. Pyrolysis heavy oils were characterized by nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The NMR analyses revealed that with increased zeolite regeneration cycles, p-hydroxy phenyl and methoxyl groups increased. Decreases in guaiacyl phenolic hydroxyl were less for the combined ‘Y + M’ sample than the individual Y and M zeolites. Lower weight average (Mw) of heavy oil for the combined ‘Y + M’ sample indicated the enhanced cleavage of lignin structures in pyrolysis. These results support the higher catalytic activity of regenerated zeolites for the combined ‘Y + M’ sample compared with individual Y and M zeolites due to the improved MSA and TAS.

Easy hydrogel preparation with high-purity lignin separated from DES pretreatment with excellent performance for moisture-electric generators and motion sensors

“…Lignin, a three-dimensional natural aromatic polymer, is abundantly found on Earth. 23 In the pulping industry, approximately 500 000 tons of industrial lignin are generated annually as a primary by-product in pulping waste liquid. 24 This lignin has immense potential as a raw material to produce high-value products, especially functional hydrogels.…”

Design of Fe3+-Rich, High-Conductivity Lignin Hydrogels for Supercapacitor and Sensor Applications

“…Lignin is a three-dimensional natural polymer that is abundantly available and contains aromatic moieties from the plant kingdom . It is one of the major byproducts of the pulping industry, and annually, its global production is about 50 million tons. , Lignin has been considered for the preparation of different value-added products, including functional hydrogels, due to its rich availability, renewable source, low cost, and unique physiochemical properties. − …”

Amphiphilic Lignin Nanoparticles Made from Lignin-Acrylic Acid-Methyl Methacrylate Copolymers

“…Lignin is a renewable natural polymer composed of phenylpropane units linked by ether bonds and is a significant byproduct of the pulp and paper industry [ 1 , 2 ]. Kraft lignin (KL) is a lignin derivative originating from the kraft pulping process that has become a representative of industrial lignin due to its significant production rate and relatively low production costs [ 3 , 4 ]. However, only about 2% of the 50 million tons/year of generated KL is used to create heat and replace fossil materials in pulp mills [ 5 ].…”