Quality Of Pyrolysis Products Research Articles

Catalytic upgrading of polyethylene plastic waste using GMOF catalyst: Morphology, pyrolysis, and product analysis

Since 2000, global plastic waste production and consumption have doubled, escalating from 250 to 500 million tonnes. Merely 9 % of plastic waste undergoes global recycling, leaving the majority either in landfills or poorly managed. This research introduces a new catalyst, GMOF, created by growing Metal-Organic Framework (MOFs) rods on the flaked, carpet-like structure of Graphene Oxide (GO) nanosheets. The aim is to enhance the quality of pyrolysis products derived from high-density polyethylene (HDPE) and low-density polyethylene (LDPE) waste using this GMOF catalyst. HDPE and LDPE, sourced from post-consumer plastic packaging, underwent specific treatment involving cleaning, drying, and shredding. Morphological and property evaluations of GO nanosheets before and after MOF decoration employed techniques including Field-Emission Scanning Electron Microscopy (FE-SEM), Energy-Dispersive X-ray Spectroscopy (EDS), and Fourier Transform Infrared Spectroscopy (FTIR). Flash pyrolysis at 500 °C for 1 min using a sample-to-catalyst ratio of 4:1 in a Quartz Wool Matrix (QWM) reactor was conducted via a Thermogravimetric Analyzer (TGA) and Frontier LAB pyrolizers. Thermal stability and characteristics of feedstocks and catalysts were assessed using TGA. Gas Chromatography-Mass Spectrometry (GC–MS) analyzed and quantified pyrolysis product compounds, while a Micro GC Fusion system determined non-condensable pyrolyzate permanent gas distribution. Results showcased that the GMOF catalyst's unique morphology efficiently captured smaller radicals on its surface, providing increased surface area for effective radical–radical interactions during pyrolysis. In HDPE pyrolysis, the GMOF catalyst notably decreased selectivity of C21-C40 and C40 + wax fractions to 49.07 % and 7.73 %, respectively, while boosting C1-C20 olefin production by 2.54 %. Conversely, LDPE pyrolysis with the GMOF catalyst notably amplified the CO2 peak intensity by 3.17 %, signifying a gasification phase. Primary gases produced were C3 aliphatic hydrocarbons, propane, and propylene, yielding 79.46 % collectively.

Influence of low-density polyethylene addition on nitrogen transformation during sludge protein pyrolysis

Co-pyrolysis of sludge and waste plastics is a long-term strategic approach for producing valuable fuels. However, sludge is characterized by a high protein content, which serves as a significant source of nitrogenous components in bio-oil. To improve the quality of pyrolysis products, the present study investigated the effect of low-density polyethylene (LDPE) on nitrogen transformation during the pyrolysis of sludge protein (SP). The study findings indicated that LDPE addition reduced the amount of solid residue owing to the interaction between SP and H radicals generated by LDPE pyrolysis. The thermal weight loss difference consistently remained below 0 when the SP-to-LDPE mixing ratio was 7:3, indicating that LDPE promotes the pyrolysis of SP. For the analysis of nitrogen-containing products during pyrolysis, LDPE addition significantly reduced the levels of nitrogen-containing compounds in the bio-oils of glutamate (Glu), histidine (His), and tyrosine (Tyr). Specifically, at 600°C, Glu, His, and Tyr in the bio-oils decreased by 31.4%, 33.3%, and 34.38%, respectively. No significant changes were observed in the nitrogen content within the pyrolysis char of Glu and His. However, all three amino acids exhibited a significant increase in the formation of NOx precursors due to the attack on the nitrogen positions of the heterocyclic nitrogen species by the H radicals generated by LDPE. This study contributes to research on the impact of LDPE on nitrogen migration and conversion during the pyrolysis of SP, laying the foundation for subsequent studies on pollutant removal reactions.

Experimental and DFT study on the effect of typical component interaction on nitrogen conversion during pyrolysis of food waste

Pyrolysis technology is an effective way to realize the reduction and recycling of food waste (FW), but the generation of N-containing substances has a great impact on the quality of pyrolysis products and the environment. The present study mainly focused on the effect of typical component interaction on nitrogen conversion during the pyrolysis of FW, which was investigated by TG-FTIR, GC-MS, and DFT calculation. The experimental results show that during pyrolysis at 500 ℃, compared with soybean protein pyrolysis, co-pyrolysis of soybean protein with rice starch reduces the production of NH3 and HCN in the pyrolysis gas and reduces the production of nitriles in the pyrolysis oil, while the production of N-containing heterocycles and amides in the pyrolysis oil increases. Soybean protein and rice starch promote the immobilization of N in pyrolysis oil through Maillard reaction and produce Maillard reaction products (MRPs). MRPs can be converted to nitrogenous heterocycles by ring formation reactions, and to amides by continued cleavage, which results in the increased yields of N-containing heterocycles and amides in the pyrolysis oil.

Effect of oxidative torrefaction on the pyrolysis of Clitocybe maxima stipe: Pyrolysis behaviour, and products' properties

In this study, oxidative torrefaction (OT) was used as the pretreatment process for the pyrolysis of Clitocybe maxima stipe (CMS) which is one kind of typical mushroom wastes, in order to evaluate the influence of OT on pyrolysis behaviour of torrefied CMS and products’ properties. The experimental results demonstrated that OT enhanced the degree of aromatization, and improved the thermal stability of the torrefied CMS compared with inert torrefaction (IT). The biochar (T9-P700) obtained by OT (9% oxygen) coupled pyrolysis (700 °C) had the improved pore structure with the highest specific surface area of 661.61 m2/g, while the obtained liquid products were less acidic with an increased formation of N-containing compounds (up to 19.15%) and phenolic compounds (8.08%). Furthermore, T9-P700 had a higher adsorption efficiency and adsorption capacity (147.31 mg/g) for Pb(Ⅱ). C-O, CO, -COOH, and -OH on the obtained biochar participated in the adsorption process of Pb(Ⅱ), attributing to the adsorption mechanism interpreted as physical adsorption, precipitation, and functional group complexation. Higher oxygen concentrations increased the severity of torrefaction, which facilitated a better pore structure in the CMS biochar generated during the subsequent pyrolysis process and the generation of liquid products with better qualities. Therefore, OT coupled pyrolysis may be an effective way to improve the quality of pyrolysis products.

Washing walnut shells with the aqueous part of pyrolysis liquids: effect on biomass and pyrolysis product quality

Washing walnut shells with the aqueous part of pyrolysis liquids: effect on biomass and pyrolysis product quality

In-situ catalytic pyrolysis of biomass with nickel salts: Effect of nickel salt type

Aiming to investigate the role of anions in the process of biomass pyrolysis catalyzed by nickel salts, four types of nickel salts (Ni(NO3)2, NiSO4, (CH3COO)2Ni, NiCl2) were impregnated on reed to investigate their effects on biomass pyrolysis. The results showed that nickel salts inhibited the release of volatiles from biomass and increased the yield of bio-char, with NiCl2 being the most effective. NiSO4 dramatically increased the specific surface area and graphitization of bio-char, and improved the selectivity of phenolic compounds in bio-oil (62.27 area%) as well as the concentration of CO in pyrolysis gas (37.78 vol%). The addition of NiCl2 enhanced the selectivity of ketone-rich oil (26.95 area%) and hydrogen-rich gas (56.39 vol%). Ni(NO3)2 is weaker than other nickel salts in catalyzing the cleavage of macromolecular compounds. This research offers a prospective approach to control the distribution and quality of pyrolysis products by using suitable catalyst precursors.

A comprehensive review on how ionic liquids enhance the pyrolysis of cellulose, lignin, and lignocellulose toward a circular economy

AbstractThe sustainable use of plant biomass (PB) to produce new valuable compounds helps alleviate the world's excessive reliance on fossil fuels. Among the different processes available, pyrolysis has drawn significant attention for its efficiency in converting PB (including lignin, hemicellulose, and cellulose) into solid, liquid, and gas products by thermal degradation. Moreover, the participation of ionic liquids (ILs) in the pyrolysis process can further facilitate this process, improve the quality of pyrolysis products, and enhance the operational parameters. This review article presents an in‐depth examination of how ILs enhance the pyrolysis of lignin, cellulose, and lignocellulose toward sustainability and circular economy (CE). The structural chemistry of the components of PB, namely cellulose, lignin, and hemicellulose, is first discussed. Furthermore, the role of ILs in the pyrolysis of cellulose, lignin, and lignocellulose is thoroughly investigated. These roles include pre‐treating agent before pyrolysis, catalyst after or during pyrolysis, template during pyrolysis, and extractant after pyrolysis. In the following, the sustainability of PB pyrolysis with the participation of ILs is examined from three aspects: environmental, social, and economical. Finally, the PB pyrolysis was investigated from the CE aspect. There is no doubt that the participation of ILs in the pyrolysis process positively affects the operating conditions and product quality, so the whole process is only one step away from complete sustainability.This article is categorized under: Sustainable Development > Sustainable Development Goals Sustainable Energy > Bioenergy Climate and Environment > Circular Economy

Experimental and DFT study on the migration and transformation mechanism of nitrogen during the pyrolysis of food waste

Pyrolysis technology is an effective way to realize the reduction and recycling of food waste (FW), but the generation of N-containing substances has a great impact on the quality of pyrolysis products and the environment. The present study mainly focused on the migration and transformation mechanism of N during the pyrolysis process of FW, which was investigated by TG-FTIR, GC–MS, and DFT calculation. The experimental results show that NH3 and HCN are the main N-containing gas products, and the N-containing substances in the pyrolysis oil are mainly N-containing heterocycles (21.82%), nitriles (6.43%), and amides (4.00%) at 500 ℃. The proteins in food waste are cleaved into various amino acid molecules at temperatures above 300 ℃. Some amino acid molecules generate NH3 and HCN by removing various groups. Some other amino acid molecules generate N-containing heterocycles, nitriles, amides, and various other N-containing substances by intramolecular de-H2O or intermolecular de-H2O reactions of amino acids or condensation reactions of amino acids with small molecules and transfer to the pyrolysis oil. As the temperature increases, most of the N-containing heterocycles and nitriles will be cleaved and generate HCN.

Effects of oxidative torrefaction on the physicochemical properties and pyrolysis products of hemicellulose in bamboo processing residues

Torrefaction pretreatment is applied to improve the fuel quality of biomass. However, in industrial production, oxygen can be unintentionally involved in the torrefaction process due to insufficient airtightness of the torrefaction reaction equipment or the presence of voids in the biomass particles. In this study, hemicellulose was extracted from the bamboo processing residue and was used as raw material for torrefaction experiment. We mainly studied the effects of oxidative torrefaction on physical and chemical properties of torrefied hemicellulose and the distribution of pyrolysis products under different oxygen concentrations and torrefaction temperatures. Results showed that a lower torrefaction temperature (200 °C) yielded solid products with higher HHV even when the oxygen concentration was increased to 15%. With a 5% oxygen concentration, a higher torrefaction temperature can apparently reduce the oxygen and hydrogen contents, and decrease atomic O/C and H/C ratios in torrefied hemicellulose. In terms of the pyrolysis products, at torrefaction temperature of 230 °C and 5% oxygen concentration, pyrolysis products had the lowest acid (7.85%) and the highest ester (6.32%) contents, indicating the highest quality of chemical compounds. A higher oxygen concentration of 5% was beneficial for the formation of alcohols in pyrolysis products. The highest content of furans (34.75%) in the pyrolysis products was achieved after torrefaction pretreatment at 260 °C and 5% oxygen concentration. The production of phenolics compounds favored lower temperature of 200 °C and 0% oxygen concentration in torrefaction pretreatment. This work provides a new avenue to improve the quality of pyrolysis products of biomass through oxidative torrefaction. Effects of oxidative torrefaction on the physicochemical properties and pyrolysis products distributions of hemicellulose derived from bamboo processing residues. • Effects of oxidative torrefaction on hemicellulose properties were investigated. • Hemicellulose underwent dehydrogenation, and deoxygenation, and less extent decarbonization during torrefaction. • Torrefaction pretreatment of hemicellulose at 230 °C and 5% oxygen concentration favored high-value pyrolysis products.

Thermogravimetric analysis of camel dung, date stone, and their blend for pyrolytic, kinetic, and thermodynamic studies

Camel dung (CM) and date stone (DS) are biomass resources that are abundant across the Gulf region and have the potential to produce sustainable renewable fuels and specialty products. Copyrolysis of CM with DS is an intriguing research approach to boosting both the production and quality of pyrolysis products, particularly biochar. The current study investigated the bio-energy potential of CM, DS, and CD-DS blend by assessing their physicochemical attributes, pyrolysis characteristics, and kinetic behaviour using thermodynamic analysis. To investigate the pyrolysis behaviour, the materials were thermally decomposed using a thermogravimetric analyser under non-isothermal conditions at different heating rates in a nitrogen environment. The findings of the physicochemical analysis established the bio-energy potential of the feedstocks for long-term energy generation. Thermal degradation profiles of the samples revealed multistage degradation due to the various components in their structure. While a positive synergistic effect between DS and CD was observed in the thermal profile of the blend. The average apparent activation energy of CD from the Friedman method, Flynn–Wall–Ozawa (FWO) model, Kissinger–Akahira–Sunose (KAS) method, and Starink model was 324, 167, 157, and 158 kJ/mol, respectively. Friedman, FWO, KAS, and Starink methods yielded average activation energies of 621, 315, 276, and 279 kJ/mol for DS, respectively. The mean activation energy of the blend estimated using the Friedman, FWO, KAS, and Starink methods was 210, 216, 206, and 207 kJ/mol, respectively. The thermodynamic outcomes reveal that slow pyrolysis of the specified feedstocks is a nonspontaneous process requiring external energy for their degradation. The findings of this study may aid in a better understanding of reaction processes and the expansion of pyrolysis applications of DS, CD, and their mix.

A review of sensor applications towards precise control of pyrolysis of solid waste and biomasses

Pyrolysis is one of the most efficient and sustainable technologies for converting biomass, solid waste into valuable bioenergy products to achieve future-oriented synthetic energy. As the intelligent automation control has been rapidly developing recently, it is desired to control and adjust the operating parameters in each feedstock reaction stage by accurately measuring the temperatures, pressures, and the produced gas quantity and compositions. This study reviews comprehensively pressure and gas sensors that are applied or potentially applied in pyrolysis. It was found that the operating temperature and reactor pressure are critical parameters affecting the yields and quality of pyrolysis products. Gas sensors can be used to detect various gases and vapors, such as methane, hydrogen, carbon monoxide, and dioxide, to estimate the quality, quantity, and compositions of gas products for their further utilizations during the pyrolysis and upgrading. According to the sensing data of the gas products, operating parameters of the pyrolysis and upgrading processes can be adjusted and optimized to enhance the pyrolysis efficiency and quality of synthetic energy products. As for the performances of available gas sensors, many of them can withstand temperatures up to 1000 °C and have advantages of good selectivity and stable for long-time, which can be utilized for pyrolysis and upgrading processes. The authors' group will develop high temperature wireless SAW gas sensor for monitoring the major gases in the reactor during pyrolysis and upgrading processes and enhance the efficiency of syn-gas production and gas quality via sensing.

Study of waste rubber catalytic pyrolysis in a rotary kiln reactor with spent fluid-catalytic-cracking catalysts

The low utilization rate of waste rubber has caused serious environmental pollution problems. Catalytic pyrolysis is an effective method for ensuring the resource utilization of waste rubber. However, the high cost and nonrecyclability of the used catalysts complicate the utilization of this method in industrial applications. In this paper, the spent fluid-catalytic-cracking (FCC) catalysts were applied into pyrolysis of waste rubber, aiming to reduce the cost of catalytic pyrolysis of waste rubber. At the same time, the pyrolysis mechanisms of the spent FCC catalysts used in waste rubber were studied. Pyrolysis/catalytic pyrolysis experiments on single-rubber-type unvulcanized rubber, single-rubber-type vulcanized rubber, and tread compounds were performed in a self-developed industrial pilot plant. The experimental results showed that the pyrolysis oil yield of the spent FCC catalysts catalyzed pyrolysis of the waste rubber increased and the content of light aromatics in increased by more than 90 %, indicating that the spent FCC catalysts applied in waste rubber can improve the quality of pyrolysis products, increase production efficiency, and realize the collaborative high-value reuse of waste rubberand spent FCC catalysts.

Recent Progress in Sludge Co-Pyrolysis Technology

With the development of society and industry, the treatment and disposal of sludge have become a challenge for environmental protection. Co-pyrolysis is considered a sustainable technology to optimize the pyrolysis process and improve the quality and performance of pyrolysis products. Researchers have investigated the sludge co-pyrolysis process of sludge with other wastes, such as biomass, coal, and domestic waste, in laboratories. Co-pyrolysis technology has reduced pyrolysis energy consumption and improved the range and quality of pyrolysis product applications. In this paper, the various types of sludge and the factors influencing co-pyrolysis technology have been classified and summarized. Simultaneously, some reported studies have been conducted to investigate the co-pyrolysis characteristics of sludge with other wastes, such as biomass, coal, and domestic waste. In addition, the research on and development of sludge co-pyrolysis are expected to provide theoretical support for the development of sludge co-pyrolysis technology. However, the technological maturity of sludge pyrolysis and co-pyrolysis is far and needs further study to achieve industrial applications.

Production of catalytic-upgraded pyrolysis products from oiltea camellia shell and polypropylene using NiCe-X/Al2O3 and ZrO2 catalyst (X = Fe, Co)

Co-pyrolysis of biomass and plastics wastes mixture into high-value products is a promising means based on the view of waste-to-energy and economic. In this study, a series of novel catalysts were prepared to product high-quality pyrolysis oil, high-value carbon nanotubes (CNTs) and hydrogen rich gas from oiltea camellia shell (OCS) and polypropylene (PP) in a two-stage catalytic pyrolysis process. The effects of active metal and support material of different pyrolysis catalysts on the characteristics of products were established. The results show that Ni-Co bimetallic catalysts showed higher hydrogen rich gas product yields. With the presence of Ni-Co bimetal, aromatic hydrocarbons reached 56.29 % (Al2O3 based) and 58.64 % (ZrO2 based). In addition, gasoline components also reached 49.55 % (Al2O3 based) and 49.57 % (ZrO2 based), which indicating that the cracking of large macromolecules was promoted. The carbon materials obtained from the NiCoCe@Al catalyst has the lowest defects and the highest degree of graphitization. NiCoCe@Al and NiCoCe@Zr catalysts showed that the filamentous carbon of over the decomposition catalysts can be judged to CNTs. Moreover, higher uniformity and lower defects of CNTs was achieved using NiCoCe@Al and NiCoCe@Zr catalysts. The efficient pyrolysis catalysts has significantly increases the quality of pyrolysis products, which were expected to enhance the large-scale promotion of biomass catalytic pyrolysis.

Recent progress in the catalytic thermochemical conversion process of biomass for biofuels

This review paper introduces various biomasses (e.g., agricultural, woody biomass waste) used in thermochemical conversion processes, including gasification, pyrolysis, and hydrothermal liquefaction. The recent advances and progress in catalytic thermochemical conversion technologies are analyzed. In particular, the role of catalysts in different reactors on the major products (bio-oil and syngas) is discussed with respect to the product yield and property. Various catalytic reaction mechanisms during the thermochemical conversion reaction are discussed to explain the conditions to enhance the desired pyrolysis product quality. Furthermore, different types of reactors for each thermochemical process are reviewed. Further processing technologies using biomass pyrolytic bio-oil products are also introduced. Finally, this review paper presents the related challenges and opportunities encountered in thermochemical conversion processes to understand better the future of thermochemical conversion processes in biorefineries.

A case study on microwave pyrolysis of waste tyres and cocoa pod husk; effect on quantity and quality of utilizable products

Disposal of huge amounts of diverse wastes for reduced costs accompanied with gaining of energy and valuable chemicals is an eager topic in waste-to-energy and fuel business. Microwave pyrolysis is a thermochemical route providing such benefits. Waste scrap tyres (ST) and cocoa pod husk (CPH) as polymer and biomass representatives were pyrolyzed in microwave reactor at 440 W power for 30 min. Quantity and quality of pyrolysis products (gas, oil, and carbon black) were investigated. It was revealed, while set microwave pyrolysis conditions are sufficient for maximum decomposition of ST to pyrolysis products, it is necessary to optimize them for CPH. The gas produced by microwave pyrolysis of ST contains more H2 and CH4 than from conventional pyrolysis, thus, microwave pyrolysis is an effective tool for production of a fuel gas. The oil obtained by ST microwave pyrolysis is a complex mixture of mostly nonpolar aromatic compounds (toluene, benzene, limonene, styrene, o-xylene), while the oil obtained by CPH microwave pyrolysis contains mainly p-cresol, phenol and its derivatives. The ST-derived carbon black shows a well-established large-volume mesoporous-macroporous structure. The CPH-derived carbon black is a low-volume macroporous material with very well-developed microporosity. A higher gross calorific value of microwave ST-derived carbon black in comparison to conventionally prepared one is caused by its higher graphitization rate. Since the surface of ST-derived carbon black is more polar than CPH-derived one and with respect to chemical purity, it could be more suitable adsorbent for polar volatile organic compounds from gaseous emissions. It is necessary to develop a microporosity in ST-derived carbon black.

Co-pyrolysis of Chinese herb residue and polypropylene over Ni, Fe, Co and Cu/AC: Co-production and formation mechanism of carbon nanomaterials, liquid oil and pyrolysis gas

The preparation of high-value fuels and carbon nanomaterials (CNMs) by co-pyrolysis of Chinese herb residue (CHR) and polypropylene (PP) is conducive to the improvement of environment and energy problems. The effect of monometallic (Ni, Fe, Co, Cu) and bimetallic (Ni/Fe, Ni/Co, Ni/Cu) loaded on activated carbon (AC) catalysts on the pyrolysis products was investigated in a two-stage fixed bed. The results showed that the synergistic effect of bimetals improved the quality of pyrolysis products. In particular, NiCo/AC significantly promoted the removal of F and improved the quality of liquid oil. Moreover, the content of over C20 in the Ni/Co group was the lowest, indicating that the secondary cracking of macromolecules was promoted. NiCo/AC also improved the yield and quality of pyrolysis gas. The content of H2 in Ni/Co group increased to 27.82%. In addition, Ni/Co group had the highest yield (more than 4 times that of blank group) and quality (ID/IG = 1.019) of CNMs. The pyrolysis gas obtained from different front-end catalytic has a great influence on the formation of back-end CNMs. The high CH4 promoted the formation of CNMs. A unique 3D graphitic carbon (GC) network was finally formed in high temperature.

Conversion of refuse derived fuel from municipal solid waste into valuable chemicals using advanced thermo-chemical process

In this study, thermo-chemical decomposition of Refuse Derived Fuel (RDF) from municipal solid waste pre-treatment plant has been conducted in pyrolytic conditions. Due to high heterogeneity, individual RDF samples are not necessarily representative of the full variety of different components present. To overcome this, five different samples of RDF with varying compositions were treated in a rotary kiln reactor. RDF feed has been characterized based on the amount of biomass and plastic content. Product (oil & char) composition and quality were analysed using different characterization techniques. It was observed that the quality of pyrolysis products varied with the feed composition and operating temperature. Maximum oil yield of oil ∼43% was obtained from RDF containing ∼77% of plastics at 500 °C. This study showed that the interaction of RDF components has a major role in the pyrolysis oil composition. The oil phase mainly consisted of n-aliphatic, branched aliphatic compounds and primary alcohols while, the aqueous phase consisted of organic acids, furans, methanol, phenols, and their derivatives along with ketones. At higher temperatures, the phenolic compounds decreased and the alcohol content was found to increase. Using solvent extraction, phenolic compounds were extracted with hexane while, ketones and acids were extracted using acetone. With high plastic content (∼85%), the char yield reduced from 55% to 30% with increase in temperature. Char samples consisted of different functional groups such as –OH and –COOH along with the micronutrients such as K, Mg and P, with pH in the range of 7.8–9.5 making it suitable for soil applications. Detailed chemical composition analysis of pyrolysis oil and char is the key to design pyrolysis process and evaluating its importance for producing the value-added chemicals.

Microwave-assisted pyrolysis of oily sludge from offshore oilfield for recovery of high-quality products

Microwave pyrolysis of oily sludge (OS) was investigated in this study. In this case, the highest oil yield (85.93 wt%) was achieved at 500 °C. The molar ratio of H/C was lower for OS char (OC) at higher pyrolysis temperatures, indicating good stability of OC owing to high degree of carbonization and aromaticity. Then, iodine adsorption value of OC reached maximum (531.2 mg/g) at 750 °C. While methylene blue (MB) uptake slightly increased with temperature and reached maximum (384.08 mg/g) at 850 °C. In order to improve the quality of pyrolysis products, different catalysts were employed in OS pyrolysis. The maximum content (64.31%) of aromatic hydrocarbon was found in PO500-10β. In addition, β-zeolite also reduced oxygenates content in oil, beneficial for stability of oil products. The gas products from catalytic pyrolysis were abundant in CO and CH4, and KOH achieved the highest CO (5.9 wt%), CH4 (16.9 wt%) and H2 (2.4 wt%) yields. Finally, a reaction mechanism pathway for OS pyrolysis was proposed to show the production routes of gas, liquid, and solid products.

Negative-carbon pyrolysis of biomass (NCPB) over CaO originated from carbide slag for on-line upgrading of pyrolysis gas and bio-oil

In this study, the feasibility and reaction mechanism of using CaO derived from calcined carbide slag in biomass pyrolysis to realize negative-carbon emission was investigated in a fixed bed reactor. The results showed that 0.06 g CO2/g biomass was fixed when the mass ratio of calcined carbide slag/biomass was 1:1. Further increasing the amount of calcined carbide slag increased a little on the yield of fixed-CO2, but the utilization efficiency of carbide slag reduced and large amounts of coke formed. As to the effect on pyrolysis products, calcined carbide slag increased the content of combustible component in pyrolysis gas (H2, CO and CH4) through CO2 absorption, catalytic decarbonylation and cracking effect, increasing the lower heating value (LHV) of pyrolysis gas. Meanwhile, calcined carbide slag favored the dehydration of sugars and furans to cyclopentanones, ketonization of acids to linear ketones, and cracking of heavy compounds to light phenols. As a result, the content of low-oxygen containing compounds in bio-oil increased at the cost of high-oxygen containing compounds. Overall, biomass pyrolysis with calcined carbide slag is a promising negative-carbon technology, which can realize negative-carbon emission and upgrade the quality of pyrolysis products at the same time.