The application and limitation of the above characterization methods for qualitative and quantitative determination of various metal active sites in Cu-based or Fe-based zeolites for NH ₃ -SCR are reviewed.

We successfully obtained soda lignin and kraft lignin with high purity and quality by the mild soda pulping process and the harsh kraft process combined with the sequential membrane separation and purification processes. Soda lignin had excellent linear structure with 88% β-O-4 aryl ethers among all the lignin interunit linkages and relatively less phenolic –OH groups as compared with kraft lignin (32% linear β-O-4 and 64% branched C–C), which provide soda lignin with better alignment along polyacrylonitrile (PAN), reduce the entanglement of the fibers, and thus double the tensile stress of the derived carbon fibers when it was blended and electrospun with PAN in the weight ratio of 1/0.25. In particular, higher aromaticity of soda lignin was effectively retained during thermostabilization as compared with kraft lignin, which enabled higher yield of the derived carbon fiber as well as enhanced mechanical performance. The improved mechanical performance of soda lignin-derived carbon fibers could also be evidenced through the increased pre-graphitic turbostratic carbon and crystallite size in the carbon fibers, as revealed by XRD and Raman spectroscopy.

One-pot synthesized OP-Fe/M22 zeolites exhibit excellent performances in NH₃-SCR reactions.

Green and efficient transformation of crude non-edible oil with a high acid value into biodiesel in one-pot under mild conditions is desirable but challenging. Herein, we created a synergistic catalytic system consisting of novel mesoporous polymeric acid (MICPHPW) and base (MICPOH) catalysts to transform crude Jatropha oil (13.0 mg KOH per g) into biodiesel via a “two-step process in single pot” strategy. The novel acid (MICPHPW) and base (MICPOH) catalysts were fabricated facilely via an anion exchange of a mesoporous ionic covalent polymer (MICP) with H₃PW₁₂O₄₀ (HPW) and KOH, respectively, where the MICP was synthesized from cheap and readily accessible chemicals using a template-free method. The acid (MICPHPW) and base (MICPOH) catalysts were systematically characterized and exhibited outstanding properties such as a rich mesoporous structure, high acid/base density (4.2 and 3.8 mmol g⁻¹), strong acid/base sites and highly dispersed active sites. These outstanding properties endowed the catalysts with high activity, which was superior to those of diverse acid and base catalysts. High biodiesel yields were obtained by MICPHPW-catalyzed esterification of oleic acid (98% yield) and by converting crude Jatropha oil (92% yield) through the synergistic catalysis of MICPHPW and MICPOH catalysts in one pot under mild conditions. The kinetics and thermodynamics of MICPOH-catalyzed transesterification were also explored. Notably, the MICPHPW and MICPOH catalysts were robust, heterogeneous, and still maintained high activities after four consecutive cycles. The efficient synergistic catalytic system increases the economic feasibility and environmental benefits of biodiesel production.

The pyrolysis process is a thermochemical conversion reaction that encompasses an intricate array of simultaneous and competitive reactions occurring in oxygen-depleted conditions. The final products of biomass pyrolysis are bio-oil, biochar, and some gases, with their proportions determined by the pyrolysis reaction conditions and technological pathways. Typically, low-temperature slow pyrolysis (reaction temperature below 500 °C) primarily yields biochar, while high-temperature fast pyrolysis (reaction temperature 700–1100 °C) mainly produces combustible gases. In the case of medium-temperature rapid pyrolysis (reaction temperature around 500–650 °C), conducted at very high heating rates and short vapor residence times (usually less than 1 s), the maximum liquid yield can reach up to 85 wt% (on a wet basis) or achieve 70 wt% (on a dry basis), with bio-oil being the predominant product. By employing the pyrolysis technique, valuable utilization of tobacco stem waste enriched with lignin can be achieved, resulting in the production of desired pyrolysis products such as transportation fuels, bio-oil, and ethanol. The present review focuses on catalytic pyrolysis, encompassing catalytic hydropyrolysis and catalytic co-pyrolysis, and meticulously compares the impact of catalyst structure on product distribution. Initially, we provide a comprehensive overview of the recent pyrolysis mechanism of lignin and tobacco waste. Subsequently, an in-depth analysis is presented, elucidating how to effectively design the catalyst structure to facilitate the efficient conversion of lignin through pyrolysis. Lastly, we delve into other innovative pyrolysis methods, including microwave-assisted and solar-assisted pyrolysis.