Pyrolysis Catalyst Research Articles

Phosphorus-modified mesoporous niobium pentoxide catalyst for fast pyrolysis of cellulose to selective production of levoglucosenone

Catalytic fast pyrolysis of biomass/cellulose is a promising way for the production of levoglucosenone (LGO) and other value-added anhydrosugars. Herein, ammonium dihydrogen phosphate (NH4H2PO4) modified mesoporous niobium pentoxide (P-Nb2O5) was first applied to selectively produce LGO. The catalyst had a stable amorphous mesoporous structure with abundant activity species (Nb-O-Nb, Nb-O-P, P-OH, and PO43-), which affected the dehydration and depolymerization reactions of cellulose to alter the competing relationship between levoglucosan (LG) and LGO. Micro-scale pyrolysis experiments demonstrated that the yield of LGO reached 19.6 wt% under the optimized condition (P loading of 50 wt%, pyrolysis temperature of 400 °C, and catalyst-to-cellulose mass ratio of 7). In lab-scale experiments, the highest yield of LGO attained 16.5 wt%, and the catalytic activity could maintain over 80% after five recycles. Overall, the P-Nb2O5 has been proven to be a promising catalyst to produce LGO from cellulose.

Microwave catalytic co-pyrolysis of sugarcane bagasse and Chlorella vulgaris over metal modified bio-chars: Characteristics and bio-oil analysis

Bio-char (BC) is a cheap, environmentally friendly and easy-to-produce material, which is widely used as pyrolysis catalyst. In this study, the modified catalysts (Fe/BC, Co/BC and Mg/BC) were prepared using BC produced by the co-pyrolysis of sugarcane bagasse and Chlorella vulgaris. The characterization of the modified catalysts showed that they had a higher surface area (SBET) and pore volume compared with BC. Besides, the influence of modified catalysts on co-pyrolysis was analyzed at different additions. Except for 10% Mg/BC, the catalysts effectively increased the average weight loss rate (Rv) and decreased the reaction time (ts) of co-pyrolysis at all additions, and 40% Fe/BC addition had the highest Rv and lowest ts. The catalyst addition increased the bio-oil yield of the co-pyrolysis, and the maximum bio-oil yield (25.94%) was obtained under 40% Mg/BC addition. Moreover, the catalysts not only facilitated the formation of hydrocarbons, but also suppressed the generation of amines/nitriles and acids/esters. After adding 40% Fe/BC, the hydrocarbons content reached the highest (26.01%), while the amines/nitriles content (3.23%) and acids/esters content (4.66%) reached the lowest. The results provided theoretical support for improving microwave pyrolysis characteristics and bio-oil quality using modified BC catalysts.

Non-Catalytic and Catalytic Conversion of Fruit Waste to Synthetic Liquid Fuel via Pyrolysis

Plum stone stands out as an alternative biomass source in terms of obtaining fuel and chemicals with or without catalysts under different conditions. Under variable heating rates (10, 50, and 100 °C min−1) and pyrolysis temperatures (400, 450, 500, 550, and 600 °C), plum stone was pyrolyzed at a constant rate in a constant sweep gas flow (100 cm3 min−1) in a tubular fixed-bed reactor. According to the results, an oil yield reaching a maximum of 45% was obtained at a heating rate of 100 °C min−1 and pyrolysis temperature of 550 °C in the non-catalytic procedure. The catalytic pyrolysis was carried out with two selected commercial catalysts, namely ZSM-5 and PURMOL-CTX and clinoptilolite (natural zeolite, NZ) under optimum conditions with a catalyst ratio of 10% of the raw material. With the addition of catalyst, the quantity and quality of bio-oil increased, including calorific capacity, the removal of oxygenated groups, and hydrocarbon distribution. In the presence of catalysts, an increase was observed in terms of desirable products such as phenol, alkene, and alkane, and a decrease in terms of undesirable products such as acids. Considering and evaluating all the results, the use of zeolite materials as catalysts in pyrolysis is a recommended option for obtaining enhanced chemicals and fuels.

Synthesis of Modified River Clay Catalyst for Valuable BTE Production via Catalytic Pyrolysis of Hazardous Plastic Waste

AbstractIn the present study, silica‐alumina rich river clay calcined at different temperatures are used as low cost natural green catalyst for the production of valuable aromatics benzene, toluene and ethylbenzene (BTE) via multiphase/Mp‐type catalytic pyrolysis of waste expanded polystyrene (WEPS). The calcined river clay catalysts are designated as RHC‐600, RHC‐700, RHC‐800 and RHC‐900 after calcination at the temperature of 600 °C, 700 °C, 800 °C, and 900 °C, respectively. Whereas, the natural river harvested clay is designated as RHC. The RHC‐800 catalyst is found to be the best catalyst for the WEPS pyrolysis due to its highest surface area of 18.83 m2/g and high silica to alumina (Si/Al) ratio of 2.23 among all other river harvested clay catalysts. The styrene content get reduced from 84.74 wt.% to 65.30 wt.% and BTE content increased from 11.38 wt.% to 23.51 wt.% when the process is switched over from thermal to Mp‐type catalytic pyrolysis using RHC‐800 catalyst. The promising results of RHC‐800 indicate that it can be an alternative to commercial catalyst for pyrolysis applications.

Catalytic Pyrolysis of Plastic Waste to Liquid Fuel Using Local Clay Catalyst

Plastics are nonbiodegradable, and safe disposal of this waste poses an environmental challenge all over the world. Catalytic pyrolysis is superior to thermal pyrolysis as it uses lower temperatures and hence less energy. The main objective of this study was to produce liquid fuel from plastic waste using indigenous clay as a catalyst through catalytic pyrolysis. The clay from Kisumu County was characterized through an X-ray fluorescence spectrometer (XRFS) and an X-ray diffractometer (XRD). The reaction setup consisted of a round-bottom flask reactor through which plastic feed and catalyst were heated in a temperature-controlled furnace. Vapor product was condensed using a Liebig type water condenser to give pyrolysis liquid product. Solid char was recovered from the flask at the end of the reaction. Optimization studies using central composite design (CCD) and response surface methodology (RSM) were performed in design expert software to predict optimal conditions of the operating variables for maximum yield of the liquid fuel. Results show that clay has a composition of silica and alumina at 64.5 wt% and 16.3 wt%, respectively, indicating high acidity of the clay, being a requirement for a good pyrolysis catalyst. For high-density polyethylene and polypropylene, the highest liquid yield of 87.23 wt% and 60.36 wt%, respectively, was at 300°C and a catalyst concentration of 10 wt%. Indigenous clay was established to be a suitable catalyst for catalytic pyrolysis of plastic waste, with the potential to replace imported catalysts since high yields of liquid fuel were obtained at lower reaction temperatures of 300-450°C, as compared to the 600°C required for thermal pyrolysis. In conclusion, waste plastics can be used to generate alternative fuel for industrial use. The liquid fuel can be used in diesel engines as a transport fuel, in turbines for electricity generation, and as a heating source in boilers and furnaces. Further studies on the modification of the surface and structure of clay are suggested to enhance its catalytic performance in the pyrolysis process for a better fuel yield.

Municipal sewage sludge product recirculation catalytic pyrolysis mechanism from a kinetic perspective

Using biochar derived from municipal sewage sludge (MSS) pyrolysis as a catalytic pyrolysis catalyst can not only achieve product recycling but also enhance conversion rate. In this study, the kinetics of MSS product recirculation catalytic pyrolysis were investigated based on non-isothermal thermogravimetric experiments. The results demonstrate that MSS noncatalytic/catalytic pyrolysis reaction involves five stages, with the main decomposition occurring between 180 and 680 °C and accounting for 53.14%–69.75% of the total mass loss. 20%-cata and 30%-cata reduced the average activation energy by 24.14% and 44.73% for the noncatalytic pyrolysis of MSS, respectively, and the catalytic effect of sludge-based biochar (S–C) allowed the appearance of the lowest activation energy earlier. MSS noncatalytic pyrolysis follows a kinetic mechanism of random nucleation and nucleation growth, whereas exponential nucleation predominate in catalytic pyrolysis. The catalysis mainly operates on macromolecular fracture breakdown and tar secondary cracking. Moreover, a plausible catalytic mechanism for MSS product recirculation catalytic pyrolysis was proposed. The results are expected to be useful in the design of efficient pyrolysis systems.

Unraveling the catalytic activity of CaClOH-rich incineration fly ash in the pyrolysis of single-use plastics

In recent years, increased population and economic growth have resulted in an explosion in demand, production, and disposal of non-biodegradable commodity plastics. Pyrolysis, the anaerobic thermochemical breakdown of plastics such as polyethylene (PE), polypropylene (PP), and polystyrene (PS) into lower molecular weight hydrocarbons with applications as fuels, waxes, and lubricants, has emerged as one of the most promising industrial technologies for the end-of-life treatment of plastics. While a range of inorganic materials have shown efficacy in catalyzing plastic pyrolysis and reducing their energetic demands, the use of existing inexpensive waste materials such as incineration fly ash (IFA) for this application has largely been overlooked. Herein, we demonstrate the viability of IFA as a catalyst for the pyrolysis of PE, PP, and PS, which account for almost 60% of all the waste plastics produced globally. The presence of IFA improved reaction conversions and liquid yields and resulted in positive outcomes for the pyrolysis of real-life plastic waste such as high density polyethylene (HDPE) detergent bottles and low density polyethylene (LDPE) plastic bags. Specifically, the pyrolysis of virgin HDPE pellets with IFA showed increased conversion from 46.7% to 92.8% and liquid yield from 35.1% to 81.6%, respectively. Through a set of control experiments, we determined that the catalytic activity of IFA could be attributed mainly to calcium hydroxychloride (CaClOH), which differed from other common calcium-containing minerals such as calcium oxide (CaO) and calcium chloride (CaCl2). Our findings demonstrate the unique catalytic possibilities offered by overlooked waste materials such as IFA in the upcycling of single-use plastics into liquid hydrocarbons and offer new insights on the use of different calcium-based catalysts for plastic pyrolysis.

Feasibility assessment of recycling waste aluminum dross as a basic catalyst for biomass pyrolysis to produce hydrogen-rich gas

Waste aluminum dross (AD) was used as a substrate on which active constituents were loaded after different activating treatments. A hydrothermal method was applied to synthesize the carbon-aluminum-based composite catalysts (C-ACC), whose pore structures, surface characteristics, and thermal stability were analyzed with the methods of XRF, SEM, and BET. Then, the feasibility of using recycled aluminum dross to catalyze biomass (bits of poplar wood, BPw) pyrolysis to produce hydrogen-rich gas was thoroughly evaluated. The results showed that aluminum dross exhibited significantly enhanced stability after the activating treatments and obtained a relatively large specific surface area and pore volume, presenting similar pore structure characteristics to aluminum oxides (Al2O3). Aluminum dross can be used as an excellent catalyst carrier. Carbon-aluminum-based composite material has a well-developed pore structure. Its specific surface area, average pore size, and pore volume are 118 m2/g, 10.3 nm, and 0.43 cm3/g, respectively, and its heat conductivity coefficient is 0.22 W/m · K. With a combination of advantages of activated carbon and Al2O3, the properties of iron-loaded carbon-aluminum composite catalysts are superior to those of active constituents and carrier materials. With these catalysts, a relatively high gas yield (43.77%) and a relatively small amount of char deposition (19.79%) have been achieved during the process of catalyzing BPw pyrolysis, with the H2 yield significantly increased to 64.24mL/g-biomass. So, it provides a new idea for oriented catalyzation of biomass pyrolysis to produce hydrogen-rich gas. Using aluminum dross as a catalyst carrier or a substitute for some part of the carrier can significantly improve the quality of hydrogen-rich gas. A new method of using aluminum dross to obtain catalysts for producing cheap biomass fuel through a pretreatment process has been put forward.

CaMoO4-enhanced Ni-CaO bifunctional catalyst for biomass pyrolysis to produce hydrogen-rich gas

The development and utilization of bifunctional catalysts facilitated hydrogen-rich gas production from biomass pyrolysis to achieve high-value biomass conversion. The effects of different secondary metals (Fe, Mo, Ce) doping and Mo addition ratios on the performance of biomass catalytic pyrolysis for hydrogen production were investigated. The results showed that the Mo0.5Ni1Ca7 catalyst had the best catalytic activity, where the H2 percentage was 69.59 vol%, and the yield reached 617.57 mLgbiomass−1. The CO2 concentration of the Mo0.5Ni1Ca7 catalyst was reduced by 10.6% compared to the Ni1Ca7 catalyst, which enhanced the adsorption performance of the catalyst. The intense interaction between Mo and Ca formed CaMoO4, which inhibited the formation of CaCO3 and promoted the dispersion of the active phase. The Mo0.5Ni1Ca7 catalyst had the largest NiO/Ni (OH)2 ratio and Mo6+/Mo5+ ratio, further enhancing the catalyst's stability and catalytic activity. Considering the effect of pyrolysis temperature on H2 concentration and yield, it was found that 600 °C was a relatively suitable catalytic pyrolysis temperature. This paper explored using Mo-modified catalysts in biomass catalytic pyrolysis for the first time, providing new ideas for developing bifunctional adsorption catalysts. Eventually, it provided a new way for biomass pyrolysis for hydrogen production technology.

Investigation on the Catalytic Cracking Mechanism of CuO on Dimethyl Sulfoxide (C2H6OS) and Surface Modification Effects: Insights from Density Functional Theory Calculations

To explore the catalytic cracking mechanism of CuO on oil shale and the catalytic activity of surface modifications of CuO on oil shale, dimethyl sulfoxide (C2H6OS) is used as a model molecule representative of organic sulfur compounds in oil shale, and the adsorption and dissociation behaviors of C2H6OS molecules on pure and OH pre-adsorbed CuO(111) surfaces were investigated by density functional theory calculations. The results indicate that C2H6OS selectively adsorbs at the Cusub sites via the S atom and decomposes through cleavage of the C–H bond prior to the breaking of the C-S bond on both surfaces. The presence of OH on the CuO(111) surface promoted the dissociation of C2H6OS. The energy barriers of dehydrogenation and desulfurization of C2H6OS on the OH pre-adsorbed CuO(111) surface were 20.0 and 19.3 kcal/mol, respectively, which are 41% and 49% lower than those on pure surfaces. The present results provide crucial guidance for the synthesis and improvement of high-performance pyrolysis catalysts specifically designed for oil shale applications. Additionally, they also present important data regarding to the thermal stability of C2H6OS in the presence of incompatible substances.

Ex Situ Catalytic Pyrolysis of Invasive Pennisetum purpureum Grass with Activated Carbon for Upgrading Bio-Oil

Energy demands keep increasing in this modern world as the world population increases, which leads to a reduction in fossil fuels. To resolve these challenges, Pennisetum purpureum, an invasive grass in Brunei Darussalam, was examined as the feedstock for renewable energy through a catalytic pyrolysis process. The activated carbon was applied as the catalyst for a simple and economical solution. The catalytic pyrolysis was executed at 500 °C (the temperature for the highest biofuel yield) for both reactors to produce the highest amount of upgraded biofuels. The biochar produced from the non-catalytic and catalytic pyrolysis processes showed a consistent yield due to stable operating conditions, from which the activated carbon was generated and used as the catalyst in this work. A significant amount of improvement was found in the production of biofuels, especially bio-oil. It was found that for catalysts, the number of phenolic, alcohol, furans, and ketones was increased by reducing the amount of acidic, aldehyde, miscellaneous oxygenated, and nitrogenous composites in bio-oils. The highest amount of phenolic compounds was produced due to a number of functional groups (-C=O and -OH) in activated carbon. The regenerated activated carbons also showed promising outcomes as catalysts for upgrading the bio-oils. The overall performance of synthesized and regenerated activated carbon as a catalyst in catalytic pyrolysis was highly promising for improving the quality and stability of bio-oil.

Study on kinetics of spent FCC catalyst applied to the living waste plastics

AbstractThe thermochemical method is one of the most potential ways to treat waste plastics. In order to reduce the energy consumption of pyrolysis, this study selected spent fluid catalytic cracking (FCC) catalyst as a catalyst for pyrolysis of waste plastics to explore the pyrolysis process of mixed waste plastics (polypropylene (PP)/polyethylene (PE)/polystyrene (PS)). The kinetic calculations show that there was a positive synergistic effect in the co‐pyrolysis of mixed plastics, which was beneficial to the reduction of activation energy. However, the participation of spent FCC catalysts can further reduce the pyrolysis temperature and activation energy of plastics, and increase the thermal degradation rate. Compared with non‐catalytic pyrolysis, the pyrolysis temperature corresponding to the maximum weight loss rate during catalytic pyrolysis was about 12 K earlier, the maximum degradation rate was about 41% higher, and the average activation energy decreased by about 22 kJ/mol. In order to further improve the catalytic efficiency of spent FCC catalysts, the spent FCC catalysts were modified by ball milling or ultrasonic method and then used for plastic pyrolysis. It was found that the modification effect of ball milling method was better than that of the ultrasonic method. Through thermodynamic analysis, it was found that the endothermic reaction occurred in the process of plastic pyrolysis and could not proceed spontaneously. The formed pyrolysis products reduced the disorder of a microscopic system. Combined with the experimental results of this paper, it can provide theoretical support for the catalytic pyrolysis of spent FCC catalysts for mixed waste plastics.

Dolomite catalyst for fast pyrolysis of waste cooking oil into hydrocarbon fuel

Dolomite as the catalyst for pyrolysis of waste cooking oil (WCO) was investigated to produce hydrocarbon fuels. Optimization of pyrolysis parameters i.e. time, temperature and catalysts loading, achieved high selectivity of WCO to diesel hydrocarbon, compared to thermal pyrolysis that produced mainly carboxylic acids. Dolomite catalysed deoxygenation of fatty acid in WCO into hydrocarbon, consequently accelerating the pyrolysis time to 75 min. Bio-oil at 68.06% yield with 57.27% selectivity towards diesel and gasoline hydrocarbons was obtained at 450 °C while using 6% of dolomite. Dolomite exhibited partial phase separation into dolomite/CaCO3 mixtures within 15 min of pyrolysis, initiated by the generated CO2 during pyrolisis of WCO. The catalyst is stable for up to three reaction cycles suggesting the activity was achieved from the synergy between the dolomite/CaCO3 phases.

Estimating the efficiency of catalysts for catalytic pyrolysis of polyethylene

The paper is devoted to investigation of the catalytic pyrolysis of high-density polyethylene (PE) in the presence of HBEA, HZSM-5 and HFER catalysts and natural clay. Catalytic pyrolysis of plastic materials is a promising method for treatment of secondary raw materials because it allows converting polymers into chemical compounds, which further serve as a source for chemical industry. Physicochemical parameters of the catalysts were estimated using various methods: IR Fourier spectroscopy, X-ray diffraction analysis, physical adsorption of N2, thermogravimetric analysis, and pyrolytic gas chromatography. Temperature dependences of PE destruction were obtained as well as the dependence of chemical composition of the catalytic pyrolysis products on the catalyst type. Two main factors were shown to determine the efficiency of cracking and the qualitative composition of products – structural and acidic parameters of the catalyst. The presence of Broensted acid sites in zeolites promoted the cracking and aromatization reactions. The possibility of using the clay sample for thermal decomposition of PE was estimated.

Methane pyrolysis and carbon formation mechanisms in molten manganese chloride mixtures

Molten manganese chloride (MnCl2) is attractive as a high-temperature liquid catalyst for methane pyrolysis (CH4 → C + 2H2). Nevertheless, the mechanism of this reaction for continuously producing high-purity hydrogen and graphitic carbon from CH4 has not been fully elucidated. In this work, we investigated the reaction kinetics and mechanism of CH4 pyrolysis in mixtures of molten MnCl2 with various monovalent or divalent chlorides. The apparent activation energies of the molten MnCl2 mixtures for CH4 pyrolysis (<230 kJ mol−1) were much lower than that of the uncatalyzed reaction (400 kJ mol−1). Among the MnCl2 mixtures, only MnCl2–KCl showed a lower apparent activation energy than pure MnCl2 (152 and 172 kJ mol−1, respectively). In addition, MnCl2–KCl produced the largest amount of CH2* and the final solid carbon product with the highest crystallinity, suggesting that this system has unique CH4 dehydrogenation and carbon formation pathways. Density functional theory calculations also predicted high concentrations of CH2* in MnCl2–KCl, as confirmed by CH2 formation being more thermodynamically favorable in MnCl2–KCl than in MnCl2. Furthermore, the generation of C2+ unsaturated intermediates from CHx* (x < 3) was thermodynamically favored, suggesting a more facile pathway for the formation of graphitic carbon layers in molten MnCl2–KCl. In addition, an NVT ab initio molecular dynamics simulation suggested that gas-phase C–C coupling was facilitated in MnCl2–KCl by the frequent reversible desorption and adsorption of CHx* intermediates. These fundamental insights into the origins of the enhanced CH4 pyrolysis performance in MnCl2–KCl could aid in the development of molten salt catalysts with enhanced reactivity.

Aromatics production from segmented co-pyrolysis of poplar sawdust and high-density polyethylene: Enhancing the synergistic effects

Catalytic co-pyrolysis of biomass and plastic waste is a promising approach for producing renewable biofuels and value-added chemicals. However, because of their different pyrolysis behaviors, the synergy between biomass and plastic is limited, and low-yield aromatics are produced. Herein, a modified segmented catalytic co-pyrolysis technology was proposed, and the effects of pyrolysis parameters were studied in detail to enhance the synergistic effect between feedstocks. For the biomass section (segment 1), catalytic fast pyrolysis (CFP) of poplar sawdust was conducted, and results showed that employing 15 wt% MgCl2 at 500 °C facilitated the production of furans. For the plastic section (segment 2), CFP of high-density polyethylene (HDPE) were performed. It was showed that instead of Y and beta zeolites, the utilization of ZSM-5 as a pyrolysis catalyst with a loading of ZSM-5/HDPE = 1.0, and a temperature of 600 °C was beneficial for the production of short-chain olefins. For the segmented co-pyrolysis of poplar sawdust and HDPE (segment 1 + segment 2), the biomass-to-plastic ratio was crucial in aromatics production. A ratio of 1:1 was found to be most effective in producing MAHs (54.8 area%), which was ∼3.9 or 1.6 times that for the separate CFP of biomass or HDPE. This was also consistent with its higher enhancement factor, confirming that the synergy between poplar sawdust and HDPE was dramatically enhanced. Finally, a segmented catalytic co-pyrolysis reaction pathway was proposed.

Metal supported hydrotalcite catalytic depolymerization of lignin: Effects of reaction parameter on compounds distribution

In this study different metal (Ni, Co and Fe) supported hydrotalcite catalysts were synthesis and it was used for lignin depolymerization. Catalytic pyrolysis reactions have been carried out at reaction temperature range of 400 to 550 °C, reaction time 30 to 120 min. with the presence of different amount of metal supported catalysts. From product distribution, it has been found that reaction temperature 500 °C was the optimal temperature for the production of maximum bio-oil yield of 32.4 wt% at reaction time of 60 min reaction. With the addition of the catalysts in pyrolysis, bio-oil significantly increased and maximum bio-oil (47.4 wt%) was found with cobalt supported hydrotalcite catalyst (Co/MgAl2O4). Other catalysts for example Ni/MgAl2O4 and Fe/MgAl2O4 catalyst exhibited bio-oil yield of 42.1 and 43.2 wt%. Different metals on MgAl2O4 showed different properties, which is affecting the lignin depolymerization during the pyrolysis. Catalytic pyrolysis produced higher amount of G-types phenolic monomer with higher bio-oil yield. This is suggesting that Co supported MgAl2O4 catalyst effectively breakdown the ether bond (COC) in the lignin. Elemental analysis and GPC of bio-oil was specified that the macromolecules structure of lignin depolymerized effectively with the using of catalysts. breaking of lignin macromolecule into small monomers phenolic compounds. Co/MgAl2O4 and Fe/MgAl2O4 was effectively encouraged the breaking of raw lignin into low molecular weight monomers as compared to others catalyst. Higher Mw and PDI were obtained for the Fe/MgAl2O4 catalytic pyrolysis reactions due to the repolymerization of monomers are promoted during pyrolysis.

Investigation of methane and ethane pyrolysis with highly active and durable iron-alumina catalyst to produce hydrogen and valuable nano carbons: Continuous fluidized bed tests and reaction rate analysis

The goal of this research work was to evaluate a novel iron-alumina catalyst for methane and ethane pyrolysis with high conversion rates to H2 with a long life time to address two major issues reported with previous catalysts. Fluidized bed tests demonstrated continuous hydrogen production while collecting carbon containing fines. During the 230 h fluid bed test the methane conversion rate to hydrogen at 700 °C remained above 80% for 160 h while creating valuable nano carbons. Similarly high catalyst lifetimes with high methane conversions have not been reported before. Ethane was more active than methane for pyrolysis with 100% conversion to H2. Transmission electron microscopy and Raman analysis of the carbon showed single and multiwall nanotubes and conglomerate nano-fibers. Ethane did not impact the allotrope of carbon formed. TGA was used to create a data array that was used for kinetic analysis and reaction model parametric regressions. Ethane had a higher rate of pyrolysis that was 2.3–2.8 times that of methane. Ethane pyrolysis was found to be more sensitive to temperature with a higher activation energy of 62 kJ/mol as compared to methane at 43 kJ/mol. The frequency factor, Ai, was significantly higher for ethane at 0.73 [[kmol/m3-sec]/[N/m2]n] compared to 0.03 for methane on the same basis. Both gases had a functional partial pressure order dependence of ∼0.6 based on the regression analysis.

Municipal solid waste incineration (MSWI) fly ash could be used as a catalyst for pyrolysis of oil-based drill cuttings from shale gas exploitation industry

Oil-based drill cuttings (OBDC) and MSWI fly ash are both hazardous wastes and are produced in huge amounts every year. OBDC are often treated by pyrolysis for recovering hydrocarbons, while municipal solid waste incineration (MSWI) fly ash is solidified and then landfilled. This study found that MSWI fly ash had the porous structure with catalytic metal element loaded on the solid acid catalyst structure. Moreover, the specific surface area and pore size of MSWI fly ash were suitable for cracking and mass transfer of hydrocarbons in OBDC. Control experiment indicated that MSWI fly ash could promote pyrolysis of OBDC by 14.5% compared with that without any catalyst. Orthogonal experiments further confirmed that the catalytic properties of MSWI fly ash were comparable to some commercial catalysts and laboratory catalysts. Thermogravimetric results showed that the pyrolysis of OBDC was divided into three stages, and the activation energy of each stage increased gradually. Kinetic analysis proved that using MSWI fly ash as catalyst could reduce the activation energy of the third stage which needed the maximum activation energy to react, so promoted the cracking of heavy hydrocarbon and enhanced the recycling rate of hydrocarbons in OBDC.

Efficient and stable Ni-supported novel porous Ca-Mg-Al complex oxide catalyst for catalytic pyrolysis of oleic acid into gasoline-kerosene rich production using methanol as a hydrogen donor: Synthesis methods and process optimization

In this study, a series of cost-effective and eco-friendly Ca-Mg-Al and Ni-modified Ca-Mg-Al catalysts were successfully synthesized with different methods (coprecipitation, impregnation and mechanical mixing method) and applied to catalytic pyrolysis vapor upgrading of oleic acid (OA) to produce gasoline-kerosene rich production using methanol as a hydrogen donor. In addition, the effects of the process parameters (catalyst type, OA to methanol ratio, pyrolysis/catalytic temperature, catalyst loading, feedstock injection volume) on the product yield and selectivity were explored, and the reuse properties and deactivation mechanism were also evaluated. Active Ni species coupled with methanol were more conducive to enhancing the catalyst activity and OA conversion and obviously increased the selectivity toward the gasoline-kerosene product. The impregnation method was favorable for the formation of NiAl2O4 species, and coprecipitation method suppressed the formation of NiAl2O4 species. The enhanced activity and deoxygenation selectivity of the coprecipitation method (NiCaMgAl) at lower pyrolysis temperatures was attributed to the abundant higher specific surface area and pore size, higher active metal oxide (Ni2+) and well-active Ni dispersion with a smaller particle size, as well as the lower acidity and partially oxidized Ni, which suppressed the NiAl2O4 spinel phase formation compared with the Ni/Ca-Mg/Al (impregnation) and Ca-Mg-Al (mixing) catalysts, which was beneficial to the decarbonylation/ decarboxylation reaction and inhibited the hydrocracking reaction of CC. Therefore, 100% conversion, 97.12% hydrocarbon yield, 54.53% gasoline and 58.80% kerosene content over NiCaMgAl catalyst were obtained under optimal conditions (pyrolysis/catalytic temperature = 450/500°C, catalyst loading = 1.5 g, feedstock injection volume = 0.1 ml/min and OA to methanol ratio = 3:1). Moreover, NiCaMgAl catalyst also demonstrated good reusability and hydrothermal stability performance due to the lower amount of coke deposition with a lower graphitized structure, which suppressed sintering.