Yield Of Liquid Products Research Articles

Depolymerization of Lignosulfonate Catalyzed by Different Solid Base Oxides to Prepare Phenolic Compounds

Lignin is the most abundant aromatic renewable polymer in nature. However, its very stable structure limits its widespread application. To achieve high-value utilization of lignin, this study used solid base oxides to depolymerize calcium lignosulfonate (CLS) for the synthesis of phenolic compounds. The catalyst precursors were prepared by hydrothermal synthesis, and the corresponding mesoporous metal oxides NiO, MgCoOx, and NiMgCoOx were obtained after calcination. MgCoOx and NiMgCoOx had similar but stronger basicity compared to NiO. While all oxides promoted the depolymerization of CLS, NiMgCoOx was identified as the best catalyst, achieving a maximum liquid product yield of 74.3 wt.% and a selectivity of phenolic compounds of 74.52% in the liquid product. In addition, NiMgCoOx showed satisfactory structural and catalytic stability. The experimental results indicated that solid base oxides can capture the active hydrogen in CLS, causing the hydrolysis reaction of ether bonds, and the resulting products continuously depolymerize or polymerize; Co present in the catalyst promotes the adsorption of hydrogen by Ni, while NiO in NiMgCoOx facilitates the adsorption of both reactants and hydrogen. The combination of Ni and Co improves hydrogenation performance.

Structural design and electronic regulation of atomically dispersed Mo-S4 sites by second shell N species reconfiguration for intensifying hydrogen spillover

Intensifying hydrogen spillover by regulating the atomic local structures catalysts is crucial for improving the hydrogenation performance, but still hugely challenging. Herein, we report a robust single-atom catalyst featuring Mo-S4 sites in the first shell modulated with N atoms in the second shell (Mo-S4-N/C) by an efficient cyclodextrin supramolecular self-assembly pyrolysis strategy for intensifying hydrogen spillover in slurry-phase hydrocracking of vacuum residue (VR). We discovered that the H2 is activated at the single-atom Mo-S4 sites efficiently and the spillover of active hydrogen is accelerated by the reconfiguration of N species in the second shell. Remarkably, the Mo-S4-N/C catalyst demonstrates excellent catalytic hydrogenation activity with high turnover frequency calculated for total metals up to 0.46 s−1, the VR per pass conversion of 61 wt.%, liquid product yield of 94 wt.%, and the low coke content of 0.6 wt.%, along with good stability, respectively. Theoretical calculations revealed that the N species in the second shell regulated the electronic structure of Mo-S4 sites, promoting the migration of active hydrogen species by reducing the transfer energy barrier of hydrogen spillover, thus enhancing the hydrogenation performance. This work proposed a strengthened hydrogen spillover mechanism from the atomic scale for hydrogenation reaction, offering novel concepts for designing and developing high-performance hydrogenation catalysts.

CO-PROCESSING OF COTTON SOAPSTOCK, COAL DUST AND POLYMER WASTE BY PYROLYSIS METHOD

The work is aimed at solving the problems of rational consumption of secondary raw materials on the basis of carbon-containing waste of industries, saturation of the market with additional products and protection of the environment from the toxic effects of waste. Aim of work: the study of the co-pyrolysis process of gossypol resin (GR) from cotton soapstock of "Shymkentmay" JSC, coal dust (CD) of Kulan deposit and plastics waste (PW) in N2 medium. The methodology of work included the establishment of optimal modes of the process, determination of yield, composition and properties of pyrolysis products. Analysis of pyrolysis products by IR spectroscopy, XRD, chromatomass spectrometry. Study of the component composition of liquid pyrolysis products by the method of extraction separation in Soxhlet apparatus into oils, asphaltenes and resins. Assessment of perspectivity of co- pyrolytic processing of carbon-containing wastes from different industries for industrial development. Results and discussion. The optimum temperature of GR pyrolysis (T=450 ⁰С) was established, at which the yield of liquid product was on average 33.01 wt.%, gas yield – 60.33 wt.%, yield of solid residue – 6.65 wt.%. The co-pyrolysis of GR and CD at 1:1 ratio and T=500 ⁰C in N2 atmosphere was investigated for the first time. A high yield of liquid product – 47.34 wt.%, low gas formation – 2.31 wt.% and a large amount of solid residue – 50.34 wt.% were observed, which is apparently due to the formation of coal semicoke and coke. The process of co- pyrolysis of GR, CD with D=90 μm and PW (PE:HPPP – 1:1) at the ratio of 1:1:1 and temperatures of 500 ⁰С-700 ⁰С in N2 atmosphere was investigated for the first time. It is shown that the main contribution to the formation of liquid products in the given temperature regimes is made by GR and PW. Conclusion. Co-processing of carbon-containing wastes was found to be of interest and practical importance, both in terms of obtaining marketable products and maintaining a safe ecology.

Study on thermal decomposition and enrichment quality of coal from Mogoin gol deposit in Mongolia

The main purpose of this study is to investigate the thermal stability and the mechanism of thermal decomposition of Mogoin gol coal, the possibility of liquefaction by pyrolysis and thermolysis, and the possibility of enriching by heavy liquids to reduce the mineral content of coal and improve its quality. Under this purpose, The Mogoin gol coal was characterized by proximate and ultimate analysis, thermogravimetry, and investigated its thermal decomposition (thermolysis and pyrolysis). Thermogravimetric analysis was performed using Japanese HITACHI TG/DTA7300 instrument and pyrolysis investigation was carried out at different heating temperatures 200–700 °C with constant heating rate 20 °C/min for 80 min. On the basis of proximate and elemental analysis results, it has been indicated that the Mogoin gol coal is high-rank coking coal. The pyrolysis of Mogoin gol coal was studied by SNOL furnace at different heating temperatures and obtained from pyrolysis products such as hard residue, tar, pyrolytic water, and gas. From pyrolysis, the yield of pyrolysis tar (6.28%) was highest at 700 °C. The experiment of thermal decomposition (thermolysis) was carried out in air closed autoclave at 350–450 °C and using hydrogen donor solvent (tetraline) with different mass ratios of coal and solvent (1:1.75; 1:1.5). In the thermolysis experiment, the yield of liquid product is highest with the coal: solvent ratio of 1:1.5 at 450 °C.

Enhanced conversion of methane to liquid-phase oxygenates via hollow ferrite nanotube@horseradish peroxidase based photoenzymatic catalysis

A novel photoenzymatic catalytic system employing hollow ferrite nanotubes and horseradish peroxidase (HRP) has been developed to significantly enhance the conversion of methane to liquid-phase oxygenates. The 1.5 % HRP-Fe3O4 HNTs demonstrated an exceptional liquid product yield of 177.87 μmol g−1 h−1 and exhibited reusability for methane photo-oxidation under ambient conditions. The physicochemical characterization revealed that the immobilization of HRP enhanced the visible light absorption and charge carrier separation efficiency. The Fe3O4 HNTs facilitated methane (CH4) molecule adsorption, while photogenerated electrons and H2O2 participated in the Fe2+-porphyrin and Fe3+-porphyrin cycle of HRP, enabling continuous generation of hydroxyl radicals, which activated CH4 to methyl radicals. In situ EPR and FTIR results indicated that CH3OH and CH3CH2OH were produced via the formation and consumption of •CH3O and •CH2 intermediates. This work presents an efficient strategy and provides new insights into the direct photo-oxidation of methane reaction through a photoenzyme catalytic system.

Study of the co-pyrolysis behavior and bio-oil characterization of walnut shell and polyethylene by thermogravimetric analyzer and bubbling fluidized bed

In the present work, co-pyrolysis experiments of walnut shell (WS), polyethylene (PE) and their blends were performed in the thermogravimetric analyzer and lab-scale bubbling fluidized bed reactor, to clarify co-pyrolysis behaviors, synergy interactions and pyrolysis oil properties. Besides, the HZSM-5 zeolite was used as the catalyst and its catalytic characteristics were studied. Results indicated that as PE mass ratio rose from 0 to 100 %, the initial temperature monotonically increased from 265.4 to 417.3 °C, while its terminal temperature progressively decreased from 668.3 to 527.5 °C, suggesting that the addition of PE was able to accelerate the pyrolysis of samples. The co-pyrolysis of blends was distinguished into three stages, with a negative interaction observed in the first stage and positive interactions found in second and third stages. Besides, in the bubbling fluidized bed experiments, the liquid phase product yield first elevated and then reduced with rising temperature, and a high temperature promoted the degradation of oxygen-containing compounds and enhanced aromatics generation. The synergistic interaction in the co-pyrolysis of WS and PE declined the liquid phase product yield while elevating the gas phase product yield. On the other hand, blending with PE facilitated the generation of alkanes and olefins, while inhibiting the contents of oxygen-containing components and aromatics, and simultaneously, the heavy oil fraction was increased. Finally, the carbon deposited on the surface of catalysts was amorphous carbons, and could be removed by oxidation process, whereas its catalytic properties progressively declined with rising cycle number, leading to a downtrend of aromatics and olefins and an opposite trend for oxygen-containing components.

Cation Enrichment Promotes High-rate CO Electroreduction to C2+ Liquid Products.

Electrochemical reduction of CO into valuable multicarbon (C2+) liquids is crucial for reducing CO2 emissions and advancing clean energy, yet mastering efficiency and selectivity in this process remains a tough challenge. Herein, we employ a surface-modification strategy using electrochemically active polymeric 1,4,5,8-naphthalenete-tracarboxylic dianhydride (PNTCDA)-modified copper nanosheets (PM-Cu) to rearrange reactive species in the electric double layer, where the PNTCDA triggers a distinctive enolization that anchor potassium ions (K+) onto the cathode surface under reduction condition. Electrochemical analysis and computational simulations revealed that this approach fine-tunes K+ distribution in the double layer, making the dehydration of hydrated K+ more efficient and reducing active water molecules at the interface, thus inhibiting the hydrogen evolution reaction while concurrently promoting CO reduction via enhanced C‒C coupling. For the first time, the PM-Cu catalyst demonstrates ampere-scale current densities with the exclusive selectivity of a C2+ liquid product yield exceeding 90%. Thus, by tailoring the local microenvironment with electrochemically active organics, it is possible to modulate CO reduction, improve sustainable energy storage, and increase industrial carbon utilization.

Influence of Synthesis Conditions on Catalytic Performance of Ni/CeO2 in Aqueous-Phase Hydrogenolysis of Glycerol without External Hydrogen Input.

The aqueous-phase hydrogenolysis of glycerol was studied in Ni/CeO2 catalytic systems prepared by incipient wetness impregnation. The operating conditions were 34 bar, 227 ºC, 5 wt.% of glycerol, and a W/mglycerol = 20 g catalyst min/g glycerol without a hydrogen supply. The effect of the catalyst preparation conditions on the catalytic activity and physicochemical properties of the catalysts was assessed, particularly the calcination temperature of the support, the calcination temperature of the catalyst, and the Ni content. The physicochemical properties of the catalysts were determined by N2 adsorption, H2-TPR, NH3-TPD, and XRD, among other techniques. A relevant increase in acidity was observed when increasing the nickel content up to 20 wt.%. The increase in the calcination temperatures of the supports and catalysts showed a detrimental effect on the specific surface area and acid properties of the catalysts, which were crucial to the selectivity of the reaction. These catalysts notably enhanced the yield of liquid products, achieving global glycerol conversion values ranging from 17.1 to 29.0% and carbon yield to liquids ranging from 12.6 to 24.0%. Acetol and 1,2-propanediol were the most abundant products obtained in the liquid stream.

Catalytic pyrolysis of apricot kernel shell over metal supported MCM-41 catalysts obtained by synthesizing sonochemical method

In this study, it is targeted to examine the efficiency of metal supported MCM-41 catalysts on the liquid product yield from pyrolysis process of apricot kernel shell selected as a biomass and to characterize the pyrolysis liquids. In the non-catalytic pyrolysis experiments, the maximum liquid yield is obtained as 21.41 % at 500 °C. At the determined optimum condition, catalytic pyrolysis process of the biomass sample is performed with metal supported MCM-41 catalysts synthesized by sonochemical method (metal: aluminium, cobalt, iron) at different ratios to biomass (1 and 2 wt %). The pyrolysis procedures of apricot kernel shell are carried out in a tubular fixed-bed reactor at different pyrolysis temperatures. The use of catalysts improved both the liquid product (tar) yield and tar quality in respect to the calorific value, the distribution of hydrocarbons and the elimination of oxygenated groups. The results revealed that all metal-supported MCM-41 catalysts, especially the Fe-MCM-41 catalyst ratio of 2, showed an excellent catalytic ability for thermal conversion of biomass. In the catalytic pyrolysis experiments carried out at 500 °C, 75.84 % conversion to liquid and gaseous products was obtained using 2 % Fe-MCM-41 catalyst, and the calorific value of the liquid product obtained was determined as 40.96 MJ/kg. The functional group analyses in the structure of the liquid products are characterized using FT-IR spectroscopy, and the distributions of the aliphatic/aromatic fractions of the liquid products are characterized using GC-MS technique. The H/C ratio of the liquid product obtained from catalytic pyrolysis is between light and heavy petroleum products and also has lower oxygen content and higher calorific value, indicating the potential of metal-supported MCM-41 catalyst for renewable hydrocarbon production from apricot kernel shell.

Recovery of methyl methacrylate from waste poly (methyl methacrylate) pellets using a low-temperature plasma and zeolites

A dielectric barrier discharge (DBD) plasma method with zeolite catalysts was applied to waste poly (methyl methacrylate) (PMMA) pellets to retrieve methyl methacrylate (MMA), methacrylic acid, and methanol at a relatively low temperature. Waste PMMA pellets were provided in the form of post-industrial recycled (PIR) PMMA. Three types of zeolite catalysts such as HY, H-zeolite socony mobil-5 (HZSM-5), and H-mobil composition of matter-22 (HMCM-22) were tested to assess their catalytic performance for retrieval under plasma irradiation. By conducting comparative examples such as non-catalytic, catalytic, and plasma-assisted non-catalytic thermolysis reactions, the cooperative effects of the DBD plasma discharge and zeolite catalyst were investigated. HMCM-22 was found to be more effective, especially for the retrieval of MMA. In the cases of non-catalytic and catalytic thermolysis at 300 °C, conversions of PMMA were found 50.9 % and 52.6 %, respectively. By contrast, plasma-assisted non-catalytic thermolysis showed that the PMMA conversion improved by up to 90.6 %, whereas the yield of MMA was relatively low (34.6 %). Using zeolite catalysts in the plasma bed also improved PMMA conversion by up to nearly 90 %. The liquid products yields were comparable for HY and HZSM-5. By contrast, HMCM-22 afforded the highest liquid product yield. Notably, the HMCM-22 case showed highest MMA yield at nearly 53.1 %, which seems highly related to a large amount of Brønsted acid sites. More importantly, the byproducts having odor issue such as methyl pyruvate and 2,3-butanedione were not produced in such a plasma-assisted catalytic or non-catalytic conversion method.

Production of a high-energy solid biofuel from biochar produced from cashew nut shells

The aim of the study is to produce a solid biofuel of high physico-mechanical and energetic quality from heat-treated cashew nut shells. Raw cashew nut shells are heat treated at 300 °C for 120 min at a heating rate of 1 °C/s. The resulting biochar is milled to 74 μm. Sugar cane molasses was incorporated into the biochar powder at a rate of 10% without the addition of water. The mass yields of solid, liquid and gaseous products obtained were 46.5%, 27.6% and 25.9% respectively. The solid biofuel produced has slightly improved physicochemical and energy properties over biochar, except ash and moisture content. Thus, the addition of binder and densification increased the ash and moisture content of the solid biofuel compared to the biochar obtained. With a higher calorific value of 33.02 MJ/kg, the solid biofuel has high water resistance and meets the quality requirements of class A1 of the NF EN ISO 17225-6 standard in terms of density and mechanical strength. Solid biofuel is ideal for use in households and biomass power stations.

Preliminary strategy and product analysis of microwave pyrolysis of waste printed circuit board

AbstractIn this study, microwave pyrolysis of waste printed circuit boards (WPCBs) was carried out in an inert atmosphere, and the effects of pyrolysis temperature and nitrogen flow rate on the yield and composition of pyrolysis products were investigated. With the increase of pyrolysis temperature, the yield of liquid product increases gradually, and the yield of solid product decreases gradually. At 600°C, the yield of each phase tends to be stable. When the temperature continues to rise, the content of H2 and CO decreases, and the content of C6 ~ C9 in the liquid product decreases. Microwave heating promotes the pyrolysis of brominated epoxy resin, which helps to improve the recovery rate of valuable substances and reduce the environmental impact of waste treatment. This study demonstrates that the microwave pyrolysis of WPCBs in nitrogen atmosphere has great potential in the green recovery process.

PRODUCTION OF SYNTHETIC HYDROCARBONS USING COBALT CATALYSTS BASED ON ZSM-5 ZEOLITE

In this work, cobalt catalysts based on zeolite ZSM˗5 were prepared by the triple impregnation method and chemically analyzed. Zirconium dioxide was used as a promoter (3 wt. %). Chemical analysis of the elemental composition and structure of the obtained catalysts was carried out using scanning electron microscopy. It is shown that the elemental composition of the catalysts with satisfactory accuracy corresponds to their given composition. Experiments for catalytic tests of the prepared catalysts were carried out on a laboratory Fischer-Tropsch synthesis unit and synthetic hydrocarbons were obtained. Comparative characterization of activity of the obtained catalysts with cobalt content of 10 % and 20 % has been carried out, dependence of carbon monoxide conversion and selectivity with respect to formation of gas hydrocarbons and yield of liquid products on temperature has been studied.

Comprehensive study of alkali lignin pyrolysis catalyzed by composite metal-modified molecular sieves for the preparation of hydrocarbon liquid fuels

Catalytic lignin pyrolysis for hydrocarbon liquid fuel production offers a viable alternative to fossil fuels. This study investigated the effects of transition metal (Fe, Co, Ni, Cu) modified composite molecular sieve catalysts on the pyrolysis product distribution and behavior of alkali lignin (AL). AL pyrolysis achieved the highest liquid product yield of 24.50 % at 600 °C, with high temperatures favoring hydrocarbon product formation. Volatile gaseous products from AL pyrolysis included H2, CO, CO2, phenolic compounds, heteroatomic compounds, and hydrocarbons. Molecular sieve catalyst additions were all favorable to the increase in hydrocarbon content. Compared with ZSM-5 and SBA-15, catalysts processed through acid etching and metal modification exhibited optimized pore structure, acid site distribution, and catalytic performance. Metal-modified composite molecular sieve catalysts (FeZS, CoZS, NiZS, and CuZS) generated more liquid products and promoted hydrocarbon formation. Notably, Cu-modified ZS catalysts exhibited superior acid site distribution and specific surface area, considerably reducing oxygenated compounds in the products. A higher catalyst-to-feedstock ratio increased the number of catalytically active sites, facilitating the cracking and deoxygenation of oxygenated components and generating more hydrocarbon products. The highest hydrocarbon yield for AL with a catalyst-to-biomass ratio of 10:1 under CuZS was 92.25 %, with 66.07 % being monocyclic aromatic hydrocarbons (MAHs) and 61.72 % benzene, toluene, ethylbenzene, and xylenes (BTEX). Additionally, kinetic and thermodynamic analyses revealed a substantial decrease in the average activation energy (Eα) of AL and a reduction in entropy value with the CuZS catalyst, indicating enhanced pyrolytic reactivity of AL. Therefore, the proposed method is highly effective for producing highly selective hydrocarbons through catalytic pyrolysis of AL.

A novel screw-type pyrolysis system for selectively producing value-added chemicals from lignocellulosic biomass

AbstractIn this study, a new unique screw-type (auger) reactor system was developed to selectively obtain valuable chemical-enriched liquid pyrolysis products. The new design has heating segments with increased temperature along the reactor tube and three-staged fractional condensing lines following pyrolysis gas ports at the end of each heating segment. To maximize liquid product yield, the effects of some parameters such as feeding rate, screw rate, and temperature profile were studied by the experiments designed with Response Surface Methodology (RSM). By fixing the maximum temperature at the last heating segment of a tubular reactor to 550 °C, the conditions for maximum liquid product yield were determined as feeder driver frequency of 21 Hz (13.6 rpm), auger driver frequency of 36 Hz (24.3 rpm), and ΔT (temperature difference between consecutive heating segments) of 66 °C. Biomass feeding rate and volumetric fullness ratio of the reactor at these conditions were 42 g min−1 and 0.58 (v/v), respectively. Under these conditions, total liquid, solid, and gas product yields were obtained as 57%, 19%, and 24%, respectively. In addition, analyses of the liquid fractions showed that valuable chemicals could be obtained selectively in a large extent by using the new design.

Continuous rotary kiln pyrolysis of cassava plant shoot system and wide speciation of oxygenated and nitrogen-containing compounds in bio-oil by HESI and APPI-Orbitrap MS

This work proposes the pyrolysis of the cassava plant shoot system biomass and a comprehensive chemical characterization of the resulting bio-oil. The highest yields of liquid products were obtained at 600 °C, with 12.6 % bio-oil (organic fraction), which presented the lowest total acid number of 65.7 mg KOH g−1. The bio-oil produced at 500 °C exhibited the highest total phenolic content of approximately 41 % GAE, confirmed by GC/MS analysis (33.8 % of the total area). FT-Orbitrap MS analysis found hundreds of oxygenated constituents in the bio-oils, belonging to the O2-7 classes, as well as nitrogen compounds from the Ny and OxNy classes. Higher pyrolysis temperatures resulted in more oxygenated phenolics (O4–7) undergoing secondary degradation and deoxygenation reactions, generating O2–3 compounds. Additional classes affected were O3–5N2–3, while O1–2N1 presented more stable compounds. These findings show that cassava bio-oils are promising sources of renewable chemicals.

Effect of process parameters on plasma partial oxidation approach for removal of leaking LPG

In order to address the challenge of preventing explosions in the accidental disposal of leaking liquefied petroleum gas (LPG), a plasma partial oxidation (PPO) approach for converting the gas into liquid products is proposed for the first time, which eliminates the explosion risk in leaking LPG from the pathway of combustible gas removal. The effect of the initial C4H10 (Simulated LPG) concentration, discharge power, and residence time on the reaction performance were investigated, and the main reaction pathway was proposed. The residence time had the greatest effect on C4H10 conversion (27.6 – 78.0%) and yield of total liquid products (26.0 – 63.9%). The rise in discharge power substantially increased the C4H10 conversion (29.9 – 51.2%) and maintained a liquid product selectivity of more than 88.0%. When the initial C4H10 concentration is lower than 5%, the C4H10 concentration can reduce directly to 1.8% at a moderate discharge power (39 W) and residence time (0.81 s), which can eliminate the risk of explosion. This article provides a new approach for the disposal of LPG spills and offers new insights into the effects of main process parameters and their mechanisms for optimizing the PPO reaction performance of converting C4H10 into liquid products.

Recycling Valuable Alkylbenzenes from Polystyrene through Methanol-Assisted Depolymerization.

The vast bulk of polystyrene (PS), a major type of plastic polymers, ends up in landfills, which takes up to thousands of years to decompose in nature. Chemical recycling promises to enable lower-energy pathways and minimal environmental impacts compared with traditional incineration and mechanical recycling. Herein, we demonstrated that methanol as a hydrogen supplier assisted the depolymerization of PS (denoted as PS-MAD) into alkylbenzenes over a heterogeneous catalyst composed of Ru nanoparticles on SiO2. PS-MAD achieved a high yield of liquid products which accounted for 93.2 wt % of virgin PS at 280 °C for 6 h with the production rate of 118.1 mmolcarbon gcatal. -1 h-1. The major components were valuable alkylbenzenes (monocyclic aromatics and diphenyl alkanes), the sum of which occupied 84.3 wt % of liquid products. According to mechanistic studies, methanol decomposition dominates the hydrogen supply during PS-MAD, thereby restraining PS aromatization which generates by-products of fused polycyclic arenes and polyphenylenes.

Recycling Valuable Alkylbenzenes from Polystyrene through Methanol‐Assisted Depolymerization

AbstractThe vast bulk of polystyrene (PS), a major type of plastic polymers, ends up in landfills, which takes up to thousands of years to decompose in nature. Chemical recycling promises to enable lower‐energy pathways and minimal environmental impacts compared with traditional incineration and mechanical recycling. Herein, we demonstrated that methanol as a hydrogen supplier assisted the depolymerization of PS (denoted as PS‐MAD) into alkylbenzenes over a heterogeneous catalyst composed of Ru nanoparticles on SiO2. PS‐MAD achieved a high yield of liquid products which accounted for 93.2 wt % of virgin PS at 280 °C for 6 h with the production rate of 118.1 mmolcarbon gcatal.−1 h−1. The major components were valuable alkylbenzenes (monocyclic aromatics and diphenyl alkanes), the sum of which occupied 84.3 wt % of liquid products. According to mechanistic studies, methanol decomposition dominates the hydrogen supply during PS‐MAD, thereby restraining PS aromatization which generates by‐products of fused polycyclic arenes and polyphenylenes.

Effect of lignin modification on the selectivity of pyrolysis products from softwood kraft lignin

The synthesis of phenol via pyrolysis of lignin can be envisaged as a prospective approach for the high-value utilization of lignin, Herein, we describe an in-depth investigation of the selective modification of lignin to effectively adjust the distribution of lignin pyrolysis products. We found that hydroxypropyl modification of lignin can facilitate the elimination of methoxy from the lignin macromolecule and improve the selectivity of phenol products. In addition, increasing the carbon number of the lignin side chains causes polymerization of pyrolysis products, which is unfavorable for the synthesis of fine chemicals via lignin pyrolysis. Conversely, an increase in lignin side-chain hydroxyl content can lead to more liquid-phase products from lignin pyrolysis, and the selectivity of phenol and its congeners will also increase. As a result, the yield of liquid products obtained via pyrolysis of lignin modified via selective oxyalkylation can reach 52 %, and the relative content of phenol and its homologs can reach 45.2 %.