Search

Peanut shells, a major economic and oil crop in China, boast an abundant availability and remarkably high lignin content compared to other agricultural residues. Previous work indicated that the modified hierarchical zeolite (Zn-ZSM-5/MCM41) was effective in promoting the conversion of intermediate macromolecules during the lignin pyrolysis reaction and enhancing the yield and selectivity of liquid products. Thereby, this study aims to improve the quality of liquid products in the ex situ catalytic microwave co-pyrolysis of peanut shells and LDPE by utilizing Zn-ZSM-5/MCM41. Employing a compound center experimental design, we optimized reaction conditions through response surface analysis. The impact of microwave pyrolysis temperature and the catalyst-to-feedstock ratio on yield distribution and liquid product selectivity was explored. Results indicated a marginal increase in liquid product yield with rising pyrolysis temperatures. Moreover, an initial increase followed by a subsequent decrease in liquid product yield was observed with an increase in the catalyst-to-feedstock ratio. Optimal conditions of 450 °C and a catalyst-to-peanut hull ratio of 2.34% yielded the highest bio-oil yield at 34.25%. GC/MS analysis of the bio-oil revealed a peak in hydrocarbon content at 68.36% under conditions of 450 °C and a catalyst-to-feedstock ratio of 13.66%. Additionally, the quadratic model effectively predicted bio-oil yield and the selectivity for major chemical components. This study underscores the potential of Zn-ZSM-5/MCM41 in optimizing liquid product quality during catalytic co-pyrolysis, offering insights into bio-oil production and its chemical composition. [ABSTRACT FROM AUTHOR]

Efficiency and accuracy are two major criteria for evaluating a test method. The thermal stability evaluation of PVC materials is now mainly based on the color change of PVC samples and Congo red test paper with manual observation as the main method, which is inefficient and imprecise. In this work, a machine vision-based evaluation system was developed to address the issues of low efficiency and poor accuracy in evaluating PVC thermal stability. During the degradation process, the color change recognition characteristics of PVC film samples and Congo red test paper were determined by analyzing the RGB SUM value and the R value, respectively. In comparison to manual observation, the machine vision-based evaluation system is more objective, efficient and accurate, and it is particularly suitable for evaluating PVC samples with similar thermal stability. Moreover, this study also resolves the issue of color mutation during the window period of the thermal stability test, and obtains the thermal degradation evolution trend through the color value change curve. This method holds great importance and application potential in guiding the processing or reprocessing of PVC materials. [ABSTRACT FROM AUTHOR]

The main purpose of this article is to explore the mechanism of action of carbon-based materials in the anaerobic digestion (AD) production of medium-chain carboxylic acids (MCCA). Currently, there are various methods to increase production, but there is no review on how carbon-based materials improve MCCA. This paper first introduced the chain elongation (CE) technology, focusing on the factors affecting the production of MCCA by AD, such as pH, temperature, the ratio of electron donor (ED) to an electron acceptor (EA), substrate type, and other related factors. This article introduces the preparation and characteristics of carbon-based materials, as well as the effect and mechanism of adding carbon-based materials to AD acid production. Finally, the shortcomings of the current research were pointed out, and future research directions were prospected, aiming to provide a reference for improving the efficiency of AD of MCCA using carbon-based materials. [ABSTRACT FROM AUTHOR]

In this work, the microwave-assisted reaction of 5-hydroxymethylfurfural (5-HMF) into valuable ether and acylated production formation was investigated with the help of molybdophosphoric acid encapsulated dendritic fibrous silica (KCC-1) as a catalyst. XRD, N2 adsorption-desorption, SEM, FT-IR, NH3-TPD, and TEM were used to analyze the physicochemical and structural properties of the synthesized catalysts. The microwave etherification of 5-HMF with ethanol was tested using synthesized catalysts. The effects of the reaction temperature, reaction time, catalytic amount, and microwave power were investigated. The resulting MPA-KCC-1 and IMPA-KCC-1 catalysts demonstrated excellent activity for the etherification of 5-HMF with ethanol, producing 5-(hydroxymethyl) furfural diethyl acetal (HMFDEA) and 5-(ethoxymethyl)furfural diethyl acetal (EMFDEA) products selectively. The significant advantages of the work are the selective production of EMFDEA at 82%, the catalyst can be easily removed via filtration, and the catalyst activity remains nearly intact even after five reaction cycles. [ABSTRACT FROM AUTHOR]

Thermal stabilizers play a crucial role in improving the thermal stability of PVC samples. However, the effect of thermal behavior of the stabilizer itself on PVC samples has been rarely reported. In this work, a metal organic framework Zn–Atz with a spatial three-dimensional structure was prepared and applied for stabilizing PVC. It was found that Zn–Atz displays both initial and long-term thermal stabilization effects on PVC. However, its long-term thermal stabilization effect is unsatisfactory due to the hydrogen chloride and unstable chlorine atom diffusion rate limitation in the pore structure of Zn–Atz. CaSt2 and triphenyl phosphite (TP) can quickly absorb hydrogen chloride and chlorine free radicals produced in the PVC thermal degradation. When utilized together with Zn–Atz, CaSt2 and TP can provide longer reaction time for the diffusion of hydrogen chloride and unstable chlorine atoms in the pore structure of Zn–Atz, to significantly improve the long-term thermal stability of PVC. Meanwhile, a possible synergistic stabilization mechanism of Zn–Atz, CaSt2 and TP was proposed. [ABSTRACT FROM AUTHOR]

Developing lauraldehyde-derived Mannich base grafted PVC materials (PVC-ML-g, g = 1, 2, 3, 4, where the lauraldehyde-derived Mannich base is abbreviated as ML) via clean and efficient strategies is an effective way to resolve the increasing diseases in humans and environmental pollution caused by toxic dioctyl phthalate (DOP) traditionally used to plasticize PVC materials. Thus, in this study, the lauraldehyde-derived Mannich base, which contains both phosphate ester groups and highly flexible long carbon chains, was grafted onto PVC chains to efficiently plasticize PVC materials. The PVC-ML-g materials displayed a lower glass transition temperature than pure PVC and were comparable to conventional DOP plasticized PVC. The good plasticization behavior in the PVC-ML-3 materials was due to the simultaneous introduction of more ester groups and mobile, unentangled longer alkyl chains into the structure of PVC, which decreased the molecular interactions between the PVC chains. Moreover, the PVC-ML-g materials showed improved thermal stability and outstanding anti-migration ability because of the covalent bonds between PVC and lauraldehyde-derived Mannich base grafts. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass is an abundant renewable resource and can be efficiently converted into bio-energy by a bio-refinery. From the various techniques available for biomass thermo-chemical conversion; microwave assisted pyrolysis (MAP) seems to be the very promising. The principles of microwave technology were reviewed and the parameters for the efficient production of bio-oil using microwave technology were summarized. Microwave technology by itself cannot efficiently produce high quality bio-oil products, catalysts are used to improve the reaction conditions and selectivity for valued products during MAP. The catalysts used to optimize MAP are revised in the development of this article. The origins for bio-oils that are phenol rich or hydrocarbon rich are reviewed and their experimental results were summarized. The kinetics of MAP is discussed briefly in the development of the article. Future prospects and scientific development of MAP are also considered in the development of this article. [ABSTRACT FROM AUTHOR]