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Copper-doped porous carbon nanospheres film (Cu@PCNF) was prepared via one-step ultrasonic spray pyrolysis (USP) for photocatalytic degradation of methyl orange (MO). The photocatalytic degradation rate reached 80% after 4 hours under sunlight, and kinetic simulation results showed that the degradation reaction was a first-order reaction. Furthermore, the degradation rate did not decrease significantly after eight experiment cycles, which indicated that the film had good reusability and durability. This film synthesis technology provided a simple and effective strategy for improving the photocatalytic performance of contaminant treatment materials.

The catalytic co-pyrolysis of torrefied poplar wood sawdust (TPW) and high-density polyethylene (HDPE) was investigated over hierarchical HZSM-5. Compared with raw PW/HDPE, the bio-oil yield from co-pyrolysis of TPW/HDPE decreased gradually while the quality of bio-oil was upgraded. With increasing torrefaction temperature from 220 to 280 °C, the amounts of acids, furans, and anhydrosugars in bio-oil were significantly reduced due to the removal of hemicellulose, whereas the production of phenols and alkenes were improved due to the enhanced hydrogen transfer reaction. In the catalytic co-pyrolysis, increasing torrefaction temperature caused an enhanced production of mono-aromatics as well as the selectivity of BTX (benzene, toluene, and xylene). Nevertheless, severe torrefaction (280 °C) lead to a rapid reduction of aromatic yield and selectivity due to the loss of cellulose. Compared to parent HZSM-5, hierarchical HZSM-5 treated with alkaline concentration (0.2–0.3 mol/L) favored the formation of mono-aromatics at the expense of polyaromatics. The maximum mono-aromatics yield of 71.75% was obtained during catalytic co-pyrolysis of 260-TPW/HDPE over 0.3-HZSM-5. The present work suggests that torrefaction pretreatment followed by the catalysis of hierarchical HZSM-5 is an efficient way to promote the production of valuable mono-aromatic hydrocarbons from biomass and plastic wastes.

High-efficiency and low-cost catalysts matter a great deal to convert solid wastes into high-value chemicals and biofuels. In this study, catalytic co-pyrolysis of wheat straw and low-density polyethylene is studied to expound the effect of a biomass-derived activated carbon catalyst on the distribution and proportion of jet fuel range hydrocarbons. The effects of the pyrolysis temperature, catalyst to feedstock ratio and LDPE to wheat straw ratio on the pyrolysis product yields and distributions are investigated. The result indicates that LDPE as a hydrogen additive with wheat straw showed a remarkable synergistic effect on increasing the proportion of aromatic products. The activated carbon catalyst with P-containing functional groups has an excellent performance in the co-pyrolysis of wheat straw and LDPE to generate aromatics through the aromatization of alkanes and olefines, the dehydroxylation and oligomerization of alkylated phenols, and the deoxygenation and aromatization of carbonyls. 95.4 area% jet fuel range hydrocarbons are acquired at a temperature of 550 °C, catalyst to feedstock ratio of 2 : 1 and LDPE to wheat straw ratio of 1 : 1. The present study provides an economical, simple and effective way to obtain high purity jet fuel range hydrocarbons from agricultural wastes and plastics.

The salvaging of the waste disposable mask was conducted in this study through catalytic pyrolysis over corn stover derived biochar catalyst combined with the boosted generation of hydrogen and mono-aromatic hydrocarbons for the first time. In the absence of biochar, up to 53 wt% of wax was observed at 550 ºC, whereas at the biochar/mask ratio of 2, around 41 wt% of liquid oil was produced without the formation of wax. The hydrogen content in the gas stream was about 26 vol% at 600 ºC for non-catalytic pyrolysis, which increased to around 55 vol% at the expense of light hydrocarbons such as methane and C

The catalytic co-pyrolysis of Douglas fir and low-density polyethylene with commercial activated carbon catalysts was investigated for the first time. Six types of activated carbon catalysts were tested and compared. The obtained liquid product contained physically separated parts being in the oil and water phases, where the percentage of the oil phase ranged from 10.10 to 64.4 wt% depending on various co-pyrolysis conditions. The oil phase of bio-oil was rich in C8–C16 aromatics and aliphatics (up to 98.6 area%) that were compatible with transportation jet fuel. In addition, the main components of the bio-oil in the water phase were phenols and guaiacols, in which high phenol selectivity (up to 92.9 area%) and phenol concentration (up to 26.4 mg mL−1) were achieved. Hydrogen, methane, carbon dioxide, and carbon monoxide were the main fractions of gaseous products, where a high concentration of methane (23.6 vol%) and carbon monoxide (39.1 vol%) could be obtained. The process was optimized based on an overall consideration of bio-oil yield, C8–C16 hydrocarbon selectivity, and phenol concentration. Furthermore, a reaction mechanism for the production of phenols and hydrocarbons was proposed. Our findings may provide a novel, green, and cost-effective route to produce phase-divided phenol-enriched chemicals and transportation jet fuels.

A carbon catalyst, which was derived from nanocellulose (NC) and doped with uniform sized and well dispersed metal nanoparticles, showed optimal performance for the generation of H2-enriched (67.4 vol%) syngas during the catalytic pyrolysis of biomass. This study provides a new route for renewable H2 production by biomass pyrolysis over a green NC-based catalyst.

Biochar catalysts derived from corn stover and Douglas fir were employed for the catalytic pyrolysis of model low-density polyethylene (LDPE) and real waste plastics. The corn stover derived biochar resulted in a liquid yield of about 40 wt% without wax formation. The liquid product comprised about 60% of C8–C16 aliphatic, 20% of mono-aromatic, and 20% of C17–C23 aliphatic hydrocarbons. The gas yield was about 60 wt% with 60–80 vol% of H2. The corn stover derived biochar tended to generate more H2 gas, and by contrast, CH4 formation was favored when employing the Douglas fir derived biochar catalyst. As for the properties of reused biochars, the biochar catalyst derived from corn stover showed much better activity and longer lifetime than Douglas fir derived biochar, which might arise from the different contents of inherent minerals in biochar catalysts. After 20 times of experimental reuses and recycles, the corn stover derived biochar still possessed high activity in degrading LDPE without wax formation. And after 10 cycles of reuse of Douglas fir derived biochar, the catalyst was still active but its activity level sharply declined with the production of amounts of wax. Additionally, real packaging plastic wastes respectively consisting of LDPE, high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS) and polyethylene terephthalate (PET) also could be effectively converted into valuable hydrocarbons and gases through using biochar catalysts, which implied that biochar catalysts could be applied to the conversion of these common waste plastics. The current study demonstrated a new and efficient conversion of various waste plastics to jet fuels and H2 by using a powerfully simple, and long-life biochar catalyst.

Microalgae biomass as a sustainable feedstock has become an attractive alternative to traditional terrestrial plants for production of renewable chemicals and biofuels. However, achieving high productivity remains as a major challenge in commercial applications. Mixotrophic culture is gaining increasing attention because the metabolic capability of some microalgae to use both photosynthesis and organic carbon leads to higher productivity than either phototrophic or heterotrophic process alone. The potential of mixotrophy for mass algal cultivation should be fully explored. In this review, the superior productivity of mixotrophic cultivation of different algal species was compared with those of phototrophic and heterotrophic culture; The synergism of carbon and energy mechanism of mixotrophic growth was discussed; Particularly, the uniqueness of metabolic regulation of microalgae under mixotrophic culture in terms of carbon recycling and forms of carbon utilized was illustrated; The application in wastewater treatment of mixotrophic culture for uptaking nutrients and organics was discussed. Additionally, the opportunities and challenges of large-scale microalgae production were proposed along with summaries of advancement in various mixotrophic culture technologies. The current literature collectively supports the great potential of mixotrophic culture in enhancing productivities of microalgal biomass and bioproducts with synergy of light and organic carbons metabolism. The findings provide insights for comprehensive understanding the key role of interaction of light and carbons on the enhancement of microalgal biomass and bioproducts under mixotrophic conditions and suggest mixotrophic algal culture should be one of the priority topics for both future research and commercialization efforts.

A novel pathway to clean production of phenol-rich bio-oil and syngas by catalytic pyrolysis of pretreated lignin was investigated for the first time. The process integrated pretreatment and catalysis. The results revealed that the optimal condition for phenol selectivity (95.5%) from unpretreated lignin pyrolysis was achieved at a pyrolytic temperature of 550 °C with catalyst/lignin ratio of 0.7. Lignin pretreatment boosted the volatile production as well as syngas formation. A significant increase in the phenol concentration (from 0.6 to 7.0 mg/mL) for pretreated lignin was achieved at pretreated temperature of 50 °C for 60 min. During the deactivation test, the catalyst exhibited a benign catalytic performance for phenol selectivity after using four times. Further, the “phenol pool” and free radical were proposed to uncover the mechanism of phenol generation from catalytic conversion of pretreated lignin. These findings pave a new and clean route to produce high-purity phenol, which could ultimately advance the utilization of lignin through facile fix-bed catalytic pyrolysis technology.

This study is motivated to increase the value of cocoa pod husk (CPH), which is currently considered as waste in the cocoa farming, by converting it to activated carbon (AC). The main goal is to co...

The torrefaction bio-oil is composed of a number of chemical compounds with low concentrations, which results in a low efficiency of its application. To improve the concentrations of high-value chemicals such as furfural in the torrefaction bio-oil, four metal chlorides and hydrochloric acid were investigated as catalysts in the torrefaction of Douglas fir by microwave heating. The number of chemical compounds in the attained bio-oil was significantly reduced with introducing MgCl2, FeCl3, and AlCl3 being into the process of torrefaction. The bio-oil obtained with these three catalysts were dominated by furfural with the concentration over 20 mg/g with the torrefaction temperature, time, and catalyst/reactant ratio of 250 °C, 10 min, and 8 wt.%, respectively. The effects of torrefaction conditions on product yield were investigated by selecting MgCl2 as the catalyst, and the results indicated that the yield of torrefied biomass decreased significantly with the increase of reaction temperature, time, and catalyst loading while the yield of bio-oil collected simultaneously was increased. Further analysis for the bio-oil suggested that low temperature, long reaction time, and high catalyst loading favored furfural production. The analysis for non-condensable gas suggested that high reaction temperature and catalyst loading promoted the methane and carbon monoxide production during torrefaction. According to bio-oil and non-condensable gas analysis, a reaction pathway was proposed to explain biomass catalytic torrefaction using MgCl2.

In this study, the microwave-assisted pyrolysis coupled with ex-situ catalytic reforming of polyethylene for naphtha range hydrocarbons, with low aromatic content, was investigated. Experimental results revealed that ZSM-5 zeolites with low SiO

Fast Hydrothermal liquefaction (HTL) has emerged as a versatile means of converting wet biomass into bio-crude oil. This study was aimed to explore a fast hydrothermal co-liquefaction (co-HTL) platform to valorize corn stover and cow manure by evaluating several reaction parameters (i.e., residence time, reaction temperature, and feedstocks mass ratio). The highest yield (over 24 wt%) of bio-crude oil was achieved under the moderate condition (400 °C, 16 min, and the mass ratio of 1:1). The Higher heating value (HHV) of bio-crude oil was around 34 MJ/kg. Up to 43% of selectivity toward phenols in bio-crude oil was gained from fast co-HTL maintained for 30 min. The properties of hydrochar were comprehensively characterized by CHNS elemental analysis, SEM, EDX, and FTIR. The highest HHV of hydrochar was 27.31 MJ/kg, suggesting the high potential as a solid fuel. CO2 as the dominant gaseous fraction were identified and quantified by GC.

The corn stover originated biochar was developed to catalyze and simplify the compositions of biocrude oil from cellulose pyrolysis. The generation of common species such as furans and (anhydro)-sugars in the biocrude oil from cellulose pyrolysis was weakened remarkably in the presence of biochars, while the formation of phenol and alkylphenols was enhanced. The formation of hydrogen was favored when the biochar was presented. For example at the temperature of 600 °C and biochar to cellulose ratio of 3, about 78 vol% of hydrogen was detected, increased from around 48 vol% for non-catalytic pyrolysis. Despite 10 cycles of reuse, the biochar remained a good activity towards promoting the generation of hydrogen and monomeric phenols. This work relates to a new access to simplify the compositions of biocrude oil and produce renewable hydrogen energy through the low-cost, simple, and highly stable biochar catalyst.

The pre-dehydration of a woody biomass waste (Douglas fir, DF) with 4.6-32 wt% of diluted sulfuric acid solutions was carried out mainly at room temperature aimed to improve the carbon yield from the thermal carbonization of pre-dehydrated biomass at 500 °C. By comparison (based on the raw DF), the pre-dehydration at room temperature increased the biochar yield and carbon retention up to about 32 wt% and 54%, respectively from that of about 22 wt% and 39% without pre-dehydration. When the pre-dehydration temperature increased to 90 °C, the biochar yield and carbon retention were sharply promoted to about 44 wt% and 76%, which was about two times higher than that of the biochar obtained without pre-treatment. This work for the first time proved the effectiveness of improving the carbon yield from lignocellulosic biomass via diluted sulfuric acid-assisted pre-dehydration at low or even room temperature.

Aldol condensation of furfural with acetone over basic catalysts allows the production of furanic adducts 4-(2-furyl)-3-buten-2-one (FAc, C8) and 1,5-di-2-furanyl-1,4-pentadien-3-one (F2Ac, C13)) that can be transformed into high-quality diesel fuels by further hydrogenation. However, the development of efficient basic catalysts and understanding of role of basic sites with different strength are still required. In this work, monoclinic and hexagonal La2O2CO3 promoted ZnO-Al2O3 catalysts were synthesized with higher concentration of medium strength basic sites and better catalytic performance as compared with La2O3 and ZnO-Al2O3. This work demonstrated that the medium strength basic sites were especially active for aldol condensation reactions.

A powerful simple biochar catalyst derived from nanocellulose was applied to the catalytic upcycling of waste plastics into H2 and liquid fuels for the first time. For the results from model low-density polyethylene (LDPE) pyrolysis, the C8-C16 aliphatics and monocyclic aromatics were dominant constitutes of the liquid product with the yields ranging from 22 to 68 wt%. At the temperature of 500 °C and biochar to LDPE ratio surpassing 3, the LDPE could be completely degraded into liquid and gas without wax production. A wax yield of 16 wt% was observed at the temperature of 450 °C and biochar to LDPE ratio of 4, which was dramatically lower than that (77 wt%) from the absence of biochar at the temperature of 500 °C. Up to 92 vol% of H2 was detected in the gaseous product with a yield of 36 wt%. The lower temperatures and higher biochar to LDPE ratios favored increasing the generation of H2 at the expense of light gas CnHm especially CH4. Moreover, this biochar catalyst was tested effectively to convert the real waste plastics including grocery bags and packaging tray into valuable liquid and H2-enriched gas.

The remarkable enhancement of phenolic monomer generation and hydrogen was achieved through catalytic pyrolysis of Douglas fir over nanocellulose derived biochar catalyst for the first time. The main compositions of produced bio-oil were phenolic monomers, furans, and naphthalenes, etc., in which the phenolic monomers were dominant compositions. And at the temperature of 650 °C and 3 of biochar to biomass ratio, the quantification results showed that the concentration of phenol was increased to 53.77 mg/mL from 15.76 mg/mL of free of biochar catalyst. The concentration of cresols were facilitated to 44.51 mg/mL from 20.95 mg/mL, while the concentration of dimethylphenols reduced to 7.76 mg/mL from 9.11 mg/mL. Up to 85.32 vol% of hydrogen was observed, increasing from 45.53 vol% of the non-catalytic process. After 15 cycles of reuse, biochar catalysts still favored to produce a much higher concentration of phenolic monomers and hydrogen than that of absence of biochar catalysts.

Activated biochars (AB-0.5, AB-1, AB-1.5, AB-2) prepared under different concentrations of an activating agent were used to manufacturing composites (ABHC-0.5, ABHC-1, ABHC-1.5, ABHC-2) based on high-density polyethylene (HDPE) by compounding and injection molding. Thermal and mechanical properties of the composites were characterized and analyzed. The addition of activated biochars improved the thermal properties of HDPE shown by Differential scanning calorimetry and Thermogravimetric analysis. Additionally, ABHC-0.5 exhibited the best flexural strength (38.66 MPa), flexural modulus (2.46 GPa), tensile strength (32.17 MPa), tensile modulus (1.95 GPa), rigidity, elasticity, creep resistance, and anti-stress relaxation ability due to the best porous structure of AB-0.5. A decrease of mechanical properties was observed in ABHC-1, ABHC-1.5, ABHC-2 compared to ABHC-0.5, which was due to the fact that the porous structure was damaged by an excessive activating agent. The results of this study provided a predictive insight in view of optimizing process parameters and establishing the meaningful relationship between biochar porous structure and its resulting composites.

The economic feasibility of a facility producing jet fuel range cycloalkanes, hydrogen and biochar via microwave-assisted catalytic pyrolysis integrated with mild hydrogenation was evaluated by modeling a 1000 metric dry tonne feedstock/day using ASPEN PLUS®. The effects of hydrogenation solvent, heat integration, and coproducing H2 or syngas were investigated in different analysis scenarios. The results indicated that the production of jet fuel could reach 47882.74 Gallon/day, with 9.58 Metric tonne/day biochar and 28200 kg/day H2 as coproducts. The lowest minimum selling price of 3.78 $/Gallon was obtained when using n-hexane as the hydrogenation solvent and coproducing H2 with heat integration. The sale of H2 offset the high production cost, resulting in a significant decrease in the minimum selling price. Sensitivity analysis indicated that the production process was greatly sensitive to total capital investment, internal rate of return, market prices of feedstock and H2.

The co-pyrolysis of pretreated lignin and soapstock was carried out to upgrade vapors under microwave irradiation. Results showed that the yield of 29.92–42.21 wt% of upgraded liquid oil was achieved under varied pretreatment conditions. Char yield decreased from 32.44 wt% for untreated control to 24.35 wt% for the 150 °C pretreated samples. The increased temperature, irradiation time and acid concentration were conducive to decrease the relative contents of phenols and oxygenates in liquid oils. The main components of the liquid oil were gasoline fraction (mono-aromatics and C5–C12 aliphatics), which ranged from 57.38 to 71.98% under various pretreatment conditions. Meanwhile, the diesel fraction (C12+ aliphatics) ranged from 13.16 to 22.62% from co-pyrolysis of pretreated lignin and soapstock, comparing with 10.18% of C12+ aliphatics from co-pyrolysis of non-pretreated lignin and soapstock. A possible mechanism was proposed for co-pyrolysis of pretreated lignin and soapstock for upgraded liquid oils.

The catalytic conversion of Douglas fir sawdust into bio-phenols on activated carbons (AC) obtained by chemical activation of corn stover with H3PO4 was investigated. Taguchi experimental design was used to optimize the preparation of AC using microwave assisted pyrolysis. Based on an overall consideration of AC yield, bio-oil yield, and phenols content, the optimized conditions were phosphoric acid to biomass ratio of 0.8, microwave power of 600 W and reaction time of 20 min. The bio-oils were rich in phenolic compounds (up to 90 area %) that mainly comprised phenol, methyl and ethyl phenol. During the catalytic pyrolysis of biomass with AC, phenolic compounds could either be derived from decomposition of lignin, followed by deoxygenation, or derived from furfurals, which were degradation products of carbohydrates. The catalytic activities of ACs were mainly owing to the well-developed porosity and abundant acidic surface functional groups. The porous structures of ACs were characterized by N2 isotherms, showing a strong dependence on the acid impregnation ratio and microwave irradiation power. The presence of acidic phosphoric-containing surface functional groups was confirmed by SEM/EDX, FTIR and NH3-TPD.

Molybdenum phosphide-based catalysts have recently exhibited excellent catalytic activities for the hydrogen evolution reaction (HER) in wide pH range conditions; the intrinsic reaction mechanism, on the other hand, has not been well established. Herein, by employing the MoP as the prototypical molybdenum phosphide-based catalyst, HER activities in both acid and neutral conditions were studied by conducting periodic density functional theory calculations. Thermodynamic analysis of hydrogen atoms absorbed on both P- and Mo-terminated surfaces were compared, as well as all the reaction energy and activation energy barriers for reactions involved in the HER process. Calculation results revealed that, in an acid condition, the Volmer-Heyrovsky and Volmer-Tafel reaction mechanisms were dominated on the P-terminated and Mo-terminated catalyst surfaces, where Heyrovsky and Volmer reactions were the rate-determining step, respectively. Additionally, water splitting was introduced to the current reaction mechanism and a small reaction activation energy barrier was revealed on the P-terminated surface. Besides, a relevant small activation energy was obtained in the Tafel reaction on the defect of the P-terminated surface in a neutral solution. Theoretical results proved that HER could take place readily on both P- and Mo-terminated catalyst surfaces via different reaction mechanisms in the acid condition from the view of atom scale. More important, computational results uncovered that HER could also occur on the P-terminated surface with the assistance of surface defect in the neutral condition, which sheds new light on the HER mechanism on transition metal phosphite-based catalysts. The doping effect on HER activity was further investigated in theory and calculation results, indicating that catalytic performance could be improved by substitutional doping of the Mo atom with metals such as Mn and W.

The activated carbons (ACs) enriched in P-containing functional groups were obtained through one-pot microwave-induced pyrolysis from corn stover activated with phosphoric acid and were further tested as the catalyst for selective monophenol production from cellulose pyrolysis for the first time. Maximum AC yield (44.3 wt %) was obtained with an acid to biomass ratio of 0.85. Increasing phosphoric acid to corn stover ratios could enhance the porosity and peak intensities of P-containing functional groups in obtained ACs. Attained ACs had an excellent catalytic performance in phenol production with the highest selectivity of phenol (99.02 % based on peak area) in the obtained organic compounds at the catalytic temperature of 450 °C. The catalytic performance of ACs remained highly selective for phenol after using two times. The experimental results indicated that P-containing groups such as −O–P, O═P, and −O–P–O– were the active reaction sites and more mespores promoted phenol production. The phenol can be...

Biogas production has been the focus of many individuals in the developing world; there have been several investigations that focus on improving the production process and product quality. In the developing world the lack of advanced technology and capital has hindered the development of energy production. Renewable energy has the potential to improve the standard of living for most of the 196 countries which are classified as developing economies. One of the easiest renewable energy compounds that can be produced is biogas (bio-methane). Biogas can be produced from almost any source of biomass through the anaerobic respiration of micro-organisms. Low budget energy systems are reviewed in this article along with various feedstock sources. Adapted gas purification and storage systems are also reviewed, along with the possible economic, social, health and environmental benefits of its implementation.

In the present study, in situ catalytic pyrolysis of Douglas fir pellets was performed in a microwave reactor. A biochar catalyst derived from corn stover biochar was prepared for the experiment. The results showed that the highest amounts of hydrocarbons (52.77% of bio-oil) were achieved from microwave-assisted catalytic pyrolysis over the biochar catalyst at a reaction temperature of 480 °C. A non-condensable gas enriched in H2, CO, and CO2 was observed and analyzed by micro-GC. The amounts of H2 and CO increased during catalytic pyrolysis compared to the non-catalytic runs. GC/MS analysis results showed that the quantity of lignin-derived guaiacols decreased dramatically with the increase of the ratio of catalyst to biomass. The biochar catalyst exhibited good selectivity towards hydrocarbon and phenol compounds, simplifying the chemical composition, reducing undesirable compounds and producing pyrolysis oil in an acceptable yield. The reaction mechanism for hydrocarbon production from catalytic pyrolysis was also analyzed.

In this study, the thermal decomposition behavior and kinetics of pyrolysis and catalytic pyrolysis of Douglas fir (DF) were investigated using thermogravimetric (TG) analysis. It was found that the heating rate was an important factor during the biomass pyrolysis process, it affected the pyrolysis though heat transfer and mass transfer through the biomass particles. The differential thermogravimetric (DTG) curves demonstrated that the role of the catalyst was to slightly reduce the temperature of biomass thermal degradation. We obtained the thermal data including the activation energy, frequency factor and reaction order by Coats–Redfern and Friedman methods. For the Coats–Redfern method, we found that the activation energy of the catalytic pyrolysis was lower than that of the non-catalytic pyrolysis. It means that the ZSM-5 catalyst increased the rate of reaction and reduced the energy required for the decomposition process. Meanwhile, the result from the Friedman method demonstrated that the reaction could be divided into two steps, which were reaction rate between 0.2 and 0.7 and a reaction rate of 0.8 based on parallelism. Addition of the ZSM-5 catalyst reduced the activation energy in the first region then increased it in the second region due to the secondary cracking of intermediate compounds which was highly affected by shape-selective catalysis. Simulation of pyrolysis and catalytic pyrolysis of DF using the obtained kinetic parameters was in good agreement with the experimental data. Py-GC/MS analysis was also carried out and indicated that the ZSM-5 catalyst had a highly positive effect on aromatic hydrocarbon production by significantly reducing oxygen-containing compounds (i.e. acids, esters, ketones/aldehydes and guaiacols) during the catalytic pyrolysis of DF.

The catalytic pyrolysis of carbohydrates over a phosphoric acid-activated carbon catalyst (ACC) was investigated to obtain phenol-rich bio-oils and syngas production in a facile fixed bed reactor for the first time. The central composite design (CCD) was adopted to optimize the experimental operating conditions of glucose catalytic pyrolysis, where the effects of reaction temperatures and ratios of catalyst to reactant on product distributions were studied. The main chemical components of the obtained catalytic bio-oils from glucose were phenols, ketones, and anhydrosugars, in which the selectivity of phenols ranged from 4.8 to 100% depending on various reaction conditions. The highest selectivity of phenols was achieved at a reaction temperature of 450 °C with a catalyst to reactant ratio of 1. Carbon monoxide, carbon dioxide, methane, and hydrogen were the main gas fractions in the gaseous products, where high concentrations of carbon monoxide (50.2%) and hydrogen (9.2%) could be attained. Additionally, the catalytic pyrolysis of cellulose with different catalyst to reactant ratios at a reaction temperature of 450 °C was also investigated and the results exhibited a similar phenomenon to that of glucose. A high selectivity of phenols (96.7%) could also be achieved integrated with a high concentration of carbon monoxide (42.1%). The mechanism of phenol generation was further discussed and the “phenol pool” was proposed to describe the catalytic function of the ACC in the catalytic conversion of volatiles into phenols. Our findings suggest that the catalytic pyrolysis of renewable and earth-abundant carbohydrates over the ACC might provide a novel and viable route to generate high-purity phenols to ultimately advance the utilization of biomass energy.

In situ and ex situ catalytic upgrading of pyrolysis vapors from Douglas fir pellets in the presence of activated carbon (AC) prepared by chemical activation was studied in a microwave pyrolyzer. The in situ catalytic upgrading configuration gave lower bio-oil yields (10.25–25.5 wt%) than ex situ catalytic upgrading configuration (20.03–32 wt%). The bio-oil yield from the in situ upgrading process was significantly affected by both catalytic reaction temperature and catalyst to biomass ratio. However, the bio-oil yield from ex situ upgrading process was only significantly affected by catalyst to biomass ratio. Bio-oils compositional analysis indicated that the ex situ upgrading process generated higher phenols concentration (4.14–19.76 mg ml−1) than in situ upgrading (4.14–9.90 mg ml−1). However, the selectivity of phenols from in situ upgrading process reflected by the peak area percentages was higher than that from ex situ upgrading. The catalyst recycling tests showed that the prepared AC catalyst can be reused for three times in phenol-rich bio-oil production via catalytic microwave pyrolysis.