Catalytic Pyrolysis Process Research Articles

Insight into the engine performance of pyro-oil synthesized through catalytic co-pyrolysis of mixed waste plastics in the presence of dolomite modified with silica and ZSM-5

The production of hydrocarbon-rich liquid fuels from mixed waste plastics through the catalytic pyrolysis process is reported including engine performance. Four different catalysts, viz., DOL, SiDOL, ZSM-5, and ZSMDOL, were prepared and characterized using XRD, FTIR, FE-SEM, and EDX. The catalytic activity was assessed in pyrolysis process to produce pyro-oils. The fuel properties were determined using various ASTM methods. The analysis showed that catalysts can change fuel properties such as viscosity, density, cloud & pour points, flash & fire points, calorific values, etc. The GC–MS results suggested a higher fraction (66–85%) of lower hydrocarbons (<C12) are formed during catalytic cracking as compared to thermal cracking (∼51%). FTIR and NMR analysis confirmed the presence of different hydrocarbons (paraffin, olefin, and aromatics) in pyro-oils. A higher percentage of aromatic hydrocarbons was seen with ZSM-5 catalyst due to diffusion of primary pyrolysis products into catalyst pores resulting in formation of aromatics via a common hydrocarbon pool and higher H/C value in the feedstock. Engine performance test with 10% pyro-oil blending enhanced the brake-thermal efficiency by 1.01–10% and reduces brake-specific fuel consumption by 8.72–10.1%. On the other hand, CO emission was reduced by 40.4%, 20%, 16.1%, 8.9%, and 6.2% when commercial diesel was blended with PO-NC, PO-DOL, PO-SiDOL, PO-ZSM, and PO-ZSMDOL, respectively. Similarly, the emissions of HC and NOx were reduced by 61% and 10.85%, respectively, when the pyro-oil blend was used. Approx. 54% reduction in carbon residue was also achieved in the case of catalytic pyro-oils blended fuel sample.

One-pot cogeneration of phenol-rich bio-oil, hydrogen-rich gas and solid carbon degradation material from reed

A newly developed two-step catalytic pyrolysis process (TSCP) based on poly-generation technology is proposed to convert reed straw (RS) into phenol-rich bio-oil, hydrogen-rich gas, and solid carbon degradation material over iron-loaded activated carbon. The effects of the first step pyrolysis temperature (T1) and catalyst composition on the product distribution and target product selectivity were investigated. When T1 was 350 °C and 10% Fe/AC catalyst was selected, the concentration of phenolic compounds and H2 peaked at 63.87 area% and 63.29 vol%, respectively. The iron-loaded activated carbon catalysts promoted the decarboxylation and decarbonylation reactions of cellulose and hemicellulose decomposition products, as well as the demethylation and demethoxylation reactions of lignin for the selective production of phenolic compounds and hydrogen gas. In addition, 94.7% quinclorac (10 mg/L) removal was achieved with 0.2 g/L 10% Fe/AC catalyst-doped pyrolysis carbon and 2 mM PMS within 90 min. This study could realize the high-value comprehensive utilization of reed and provide a reference for the full quantitative utilization of other agricultural and forestry wastes.

Influence of Catalyst on the Yield and Quality of Bio-Oil for the Catalytic Pyrolysis of Biomass: A Comprehensive Review

In the modern world, as the population rises and fossil fuel supplies decline, energy demands continue to rise. Moreover, the use of fossil fuels harms the ecology, contributing to pollution and global warming. In order to overcome these difficulties, several approaches are revealed, such as the utilization of biomass as a renewable source of energy. Studies revealed that biomass can be converted into bioenergy via several thermal conversion processes, like pyrolysis, gasification, and torrefaction. Pyrolysis is the most convenient process to obtain three different types of biofuels (biochar as a solid, bio-oil as a liquid, and syngas as a gas). The biofuels produced in this process are normally lower in quality and cannot be used directly as fuel because they contain many undesirable components. Catalytic pyrolysis is one of the best processes to upgrade the quality of biofuels. Several varieties of catalysts are used in the catalytic pyrolysis process (ex situ and in situ). Due to stable operating conditions, both catalytic and non-catalytic pyrolysis procedures produce biochar that has a consistent output. Meanwhile, the effects of catalysts in the catalytic pyrolysis process considerably enhance the quality and quantity of bio-oils and syngas. By removing the unwanted oxygenated and nitrogenous components, the bio-oils produced through the catalytic pyrolysis method have a higher calorific value, reduced viscosity, and improved stability. Many researchers have looked at ways to increase the rate of pyrolysis, whereas a few have focused on maximizing the effects of the factors in order to improve the efficiency of catalytic pyrolysis. This review addresses the impact of catalysts on the catalytic pyrolysis of biomass to enhance the quality of the bio-oils in great detail. Machine learning and techno-economic analysis were investigated, as well as the future potential of the catalytic pyrolysis method for the generation of bio-oil.

Effect of MgCl2 Loading on the Yield and Performance of Cabbage-Based Biochar.

Converting more CO2 absorbed by plant photosynthesis into biomass-activated carbon effectively reduces carbon emissions. In this study, we used a one-step preparation of biomass-activated carbon loaded with MgO nanoparticles to investigate the effect of Mg loading on the catalytic pyrolysis process. The influences of magnesium loading on biochar yield and fixed carbon production were assessed. The addition of 1% Mg weakened the carbonyl C=O, inhibited the dehydroxylation reaction, enhanced the C-H signal strength, and the formation of MgO inhibited the weaker- bound substituent breakage. Additionally, the addition of magnesium altered the morphological features and chemical composition of the biochar material. It also increased the activated carbon mesoporosity by 3.94%, biochar yield by 5.55%, and fixed carbon yield by 12.14%. The addition of 1% Mg increased the adsorption capacity of the activated carbon to potassium dichromate, acid magenta, methylene blue, and tetracycline effluents by 8.71 mg, 37.15 mg, 117.68 mg, and 3.53 mg, respectively. The results showed that MgCl2 played a significant role in promoting the thermal degradation of biomass and improving the solid yield and adsorption performance of activated carbon.

Studi Karakteristik Komposisi Produk Katalitik Pirolisis TKKS dengan katalis Al White

Bio-oil can be produced from biomass which has the potential to become an environmentally friendly renewable energy source. Most of the biomass is found as organic waste or used as mulch. Therefore, this renewable energy source needs to be developed so that its utilization can be maximized as a promising energy source with a catalytic pyrolysis process. The raw material used in this research is empty palm fruit bunches (EFB). The purpose of this study was to determine the effect of catalytic pyrolysis temperature on pyrolysis products in the form of char, bio-oil and gas. The experiment was carried out at various temperatures of 300°C, 350°C and 400°C using Al white catalyst. The ratio of Al white catalyst with EFB is 1:2 mixed with the catalyst in the pyrolysis reactor. The desired temperature for the pyrolysis process can be set on the reactor temperature controller. The results showed that the optimum bio-oil production rate of 55.81% was obtained from samples at 350 °C. Bio-oil in this study was divided into BO (bio-oil in the oil phase) and BA (bio-oil in the liquid phase). In this study the bio-oil obtained at process temperatures of 300°C, 350°C and 400°C were 45.28%, 55.81% and 47.40%, with a heating rate of 5.93°C/minute , 6.11 °C/minute, and 6.68 °C/minute and the density of bio-oil ranges from 1.114–1.264 g/ml. BO products are thicker than BA products. BO viscosity is higher at high pyrolysis temperature as well. The most char products at 300oC and the most gas products at 400oC. The higher the pyrolysis temperature, the more gas will be produced. By improving the pyrolysis process, promising bio-oil can be produced with temperature, catalyst treatment, and heating rate playing an important role in it

Towards fuels production by a catalytic pyrolysis of a real mixture of post-consumer plastic waste

The contribution provides a valorization alternative for rejected plastic wastes from mechanical-biological treatment (non-recyclable material) via an in-situ catalytic pyrolysis process focused on the production of a liquid fraction with similar properties to traditional fuels (i.e., gasoline, kerosine, and diesel). According to the ASTM recommendations, on small samples without prior physical separation, fuel fraction identification was carried out by Simulated Distillation along with a hydrocarbon types analysis and complemented with CHNS-O analysis and Fourier Transform Infrared Spectroscopy. Two catalytic structures were employed named Sepiolite and Montmorillonites, both K10 and K30, which after simple heat treatment to stabilize the structure, were characterized to analyze the main properties affecting the catalytic activity and product yields (i.e., morphological and acidity properties). A whole screaming of the products by analogy with hydrocarbon of the petroleum industry is presented. Such an approach allows a real evaluation of the studied technology in the current energy scenario.

Marble sludges as environmentally friendly catalyst in olive pomace pyrolysis: Effect of sludge composition on pyrolysis product distribution and biochars

Waste management of olive pomace is difficult because of the high production amount and nonbiodegradable organic substances. Catalytic pyrolysis process is one of the effective methods for olive pomace (OP) management and for obtaining valuable organic substances from it. Therefore, in this study, different types of marble sludge were used as catalyst in the olive pomace pyrolysis process at 500°C temperature and 40% catalyst dose. While K1, K2, K3 are the sludges obtained from physicochemical treatment of travertine type marble processing wastewater with alum, FeCl3 and PEL, respectively, K4, K5 and K6 are the corresponding physicochemical treatment sludges of natural stone type marble processing wastewater. Pyrolysis product yields and characteristics of pyrolysis biochars were investigated. The highest product yield for biochar liquid and gas fractions was obtained with the K1 catalyst. The biochar obtained for OP+K1 pyrolysis has the highest initial decomposition temperature. Biochar obtained by using K6 was more granular. Biochar having the highest calorific value (1193 cal/g) was obtained with the catalytic pyrolysis of OP with K4 catalyst. Biochars obtained with the K1 and K6 catalysts has similar calorific values. Besides calorific values, the characteristics of biochars indicated that these biochars can be used diverse purposes either as additive or feedstock. Consequently, K1 catalyst can be recommended for olive pomace catalytic pyrolysis when biochars are evaluated in terms of product yield and biochar characteristics.

Recent Advances of Triglyceride Catalytic Pyrolysis via Heterogenous Dolomite Catalyst for Upgrading Biofuel Quality: A Review.

This review provides the recent advances in triglyceride catalytic pyrolysis using heterogeneous dolomite catalysts for upgrading biofuel quality. The production of high-quality renewable biofuels through catalytic cracking pyrolysis has gained significant attention due to their high hydrocarbon and volatile matter content. Unlike conventional applications that require high operational costs, long process times, hazardous material pollution, and enormous energy demand, catalytic cracking pyrolysis has overcome these challenges. The use of CaO, MgO, and activated dolomite catalysts has greatly improved the yield and quality of biofuel, reducing the acid value of bio-oil. Modifications of the activated dolomite surface through bifunctional acid-base properties also positively influenced bio-oil production and quality. Dolomite catalysts have been found to be effective in catalyzing the pyrolysis of triglycerides, which are a major component of vegetable oils and animal fats, to produce biofuels. Recent advances in the field include the use of modified dolomite catalysts to improve the activity and selectivity of the catalytic pyrolysis process. Moreover, there is also research enhancement of the synthesis and modification of dolomite catalysts in improving the performance of biofuel yield conversion. Interestingly, this synergy contribution has significantly improved the physicochemical properties of the catalysts such as the structure, surface area, porosity, stability, and bifunctional acid-base properties, which contribute to the catalytic reaction's performance.

Production of combustible fuels and carbon nanotubes from plastic wastes using an in-situ catalytic microwave pyrolysis process

This study performed in-situ microwave pyrolysis of plastic waste into hydrogen, liquid fuel and carbon nanotubes in the presence of Zeolite Socony Mobil ZSM-5 catalyst. In the presented microwave pyrolysis of plastics, activated carbon was used as a heat susceptor. The microwave power of 1 kW was employed to decompose high-density polyethylene (HDPE) and polypropylene (PP) wastes at moderate temperatures of 400–450 °C. The effect of plastic composition, catalyst loading and plastic type on liquid, gas and solid carbon products was quantified. This in-situ CMP reaction resulted in heavy hydrocarbons, hydrogen gas and carbon nanotubes as a solid residue. A relatively better hydrogen yield of 129.6 mmol/g as a green fuel was possible in this process. FTIR and gas chromatography analysis revealed that liquid product consisted of C13+ fraction hydrocarbons, such as alkanes, alkanes, and aromatics. TEM micrographs showed tubular-like structural morphology of the solid residue, which was identified as carbon nanotubes (CNTs) during X-ray diffraction analysis. The outer diameter of CNTs ranged from 30 to 93 nm from HDPE, 25–93 nm from PP and 30–54 nm for HDPE-PP mixure. The presented CMP process took just 2–4 min to completely pyrolyze the plastic feedstock into valuable products, leaving no polymeric residue.

A catalyst acid property-included stoichiometric coefficient model for catalytic pyrolysis of hydrocarbon mixtures

Process modeling is considered an effective way to achieve refined management in the petrochemical industry, and is also the foundation and necessary link of intelligent chemical platform construction. This study aims to the simulation of the formation of gaseous products for the catalytic pyrolysis of representative naphtha compositions using a stoichiometric coefficient model. Firstly, the interaction mechanism of n/cyclo-paraffins was investigated using a pseudo-first-order kinetic model, and the cracking activity of hydrocarbon mixtures was quantified using the carbon number and cyclo-paraffin content. Subsequently, a database of the stoichiometric coefficients of the gaseous products was constructed. Considering the acid properties of the catalysts, a catalyst acid property-included stoichiometric coefficient model was developed to adapt to varying feedstock composition and catalyst systems, which could reflect gaseous production in the catalytic pyrolysis of multi-component mixed hydrocarbons. Moreover, the simulation using the present model shows that the production of light olefins in the catalytic pyrolysis of mixed hydrocarbons can be increased under the optimized catalyst acid properties. Hence, this study aims to provides theoretical guidance for the prediction of product distribution as well as the design and selection of catalysts used in the catalytic pyrolysis processes for multi-component mixed hydrocarbon.

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.

Pyrolysis behaviors of biomass tar-related model compounds catalyzed by Ni-modified HZSM-5 molecular sieve

To study the pyrolysis process and path of biomass tar, this paper took toluene as the biomass tar model compound, elected Ni-modified HZSM-5 molecular sieve as the catalyst, and established the catalytic pyrolysis process of toluene. By optimizing the process conditions of HZSM-5 catalyst modification and catalytic pyrolysis process of toluene, and comprehensively considering the indicators of catalyzing pyrolysis of toluene as biomass tar model compound, the pyrolysis behavior of aromatic tar model compounds catalyzed by Ni-modified HZSM-5 catalyst was deeply analyzed. Finally, the stability of the Ni-modified HZSM-5 catalyst was investigated with a pyrolysis time of 8 h. The best process conditions of Ni-modified HZSM-5 catalyst were obtained: SiO2/Al2O3 of 25, Ni loading of 8 wt%, and pyrolysis temperature of 700 ℃. The catalytic pyrolysis path of toluene as biomass tar model compound was clarified for the cracking and reforming of toluene for gas production, condensation and reforming reaction of liquid phase, and action of carbon deposition. The Ni-modified HZSM-5 molecular sieve shows excellent catalytic properties and application prospects, providing theoretical reference and data support for further designing and enhancing the structure of such catalysts and promoting tar removal efficiency.

Feasibility Study of Plastic Waste Pyrolysis from Municipal Solid Waste Landfill with Spent FCC Catalyst

Globally, there is growing concern about the problem of plastic waste. The majority of plastic waste is dumped into landfills, where it occupies space, reducing landfill capacity and causing a variety of environmental issues. Plastic waste pyrolysis has gained popularity because it can reduce the volume of plastic waste while also producing alternative fuels. This study assessed the feasibility of producing fuel oil from plastic waste using the catalytic pyrolysis process. Polyethylene (PE), polypropylene (PP), and polystyrene (PS) waste samples were collected from municipal solid waste (MSW) landfills on Samui Island, Surat Thani Province, Thailand. Pyrolysis was carried out in a 3-L bench-scale reactor at 450ºC using a 3% spent FCC catalyst. PE, PP, PS, and mixed plastic waste were used as feedstocks. The results showed that the pyrolysis of PS produced the most liquid product (91.44 wt%), whereas the pyrolysis of PE produced the highest percentage of diesel range product (36.60 wt%). Furthermore, the results of the analysis revealed that the characteristics of diesel from improved PE pyrolysis oil by naphtha removal were similar to those of commercial diesel B7. According to the cost-benefit analysis, the operating costs of pyrolysis oil and improved diesel were 0.37 and 0.65 USD/L, respectively, which were lower than the current market price of diesel B7. The findings of the study demonstrated the feasibility of converting plastic waste from MSW on Samui Island into alternative energy using eco-friendly and cost-effective technology.

Thermodynamic appraisal of naphtha to light olefins based on different reaction pathways and independent chemical reactions

Catalytic pyrolysis of naphtha involves a series of complex acid-catalyzed reaction pathways, that significantly affect the distribution of pyrolysis products. To determine the optimal catalyst characteristics for enhancing light olefins, n-pentane and cyclopentane were used as model compounds to analyze cracking pathways, including the protolytic, dehydrogenation, and hydrogen transfer cracking pathways based on thermodynamic methods. The effects of temperature and pressure on cracking pathways are also discussed. The results indicate that the optimum cracking pathways for enhancing light olefins were the dehydrogenation cracking pathway of n-paraffins and the protolytic cracking pathway of cycloparaffin. Therefore, the design and development of catalysts with dehydrogenation and acidic active sites have become particularly important for the efficient conversion of n/cyclo-paraffins. Furthermore, a thermodynamic equilibrium model based on one set of independent reactions in the catalytic pyrolysis process was established to analyze the effects of the operating conditions on the equilibrium yields. Under these operating conditions, as determined by applying the thermodynamic equilibrium model, the production of light olefins can be tailored.

In-depth study of kinetics, thermodynamics, and reaction mechanism of catalytic pyrolysis of disposable face mask using spent adsorbent based catalysts

Millions of face mask has been converted to waste since the onset of COVID-19 virus. Hence, present study explores the feasibility of converting disposable face masks to energy through catalytic pyrolysis process using a low-cost waste (spent aluminum hydroxide/oxide nanoparticle adsorbent) derived catalyst. Thermogravimetric analysis of the non-catalytic and catalytic pyrolysis of disposable face mask was conducted at varied heating rates of 10 °C/min, 20 °C/min, 30 °C/min, 40 °C/min, and 50 °C/min, respectively. Iso-conversional methods, Kissinger Akahira Sunose (KAS) and Ozawa Flynn Wall (OFW) were used for the kinetic study. The reaction mechanism was analyzed using Criado's z-master plot (CZMP) method along with the determination of thermodynamic parameters of the process. Results found that the addition of a catalyst to the process benefits the overall efficacy of the process by reducing the activation energy (Ea) (without catalyst; OFW-Ea: 188.7 kJ/mol, KAS-Ea: 186.2 kJ/mol) as well as lowering the disordered state of the process. Metal doped catalyst (Ni/ γ-Al2O3) (OFW-Ea: 168.4 kJ/mol, KAS-Ea: 167.8 kJ/mol) shows a larger reduction in activation energy in comparison to bare alumina (γ-Al2O3) (OFW-Ea: 183.2 kJ/mol, KAS-Ea: 180.4 kJ/mol). The current study presented disposable face masks as reclaimable in terms of energy and waste-derived catalyst as a potent solution to be explored in place of high-cost commercial catalysts.

Biochar-Assisted Catalytic Pyrolysis of Oily Sludge to Attain Harmless Disposal and Residue Utilization for Soil Reclamation.

Pyrolysis of oily sludge (OS) is a feasible technology to match the principle of reduction and recycling; however, it is difficult to confirm the feasible environmental destination and meet the corresponding requirements. Therefore, an integrated strategy of biochar-assisted catalytic pyrolysis (BCP) of OS and residue utilization for soil reclamation is investigated in this study. During the catalytic pyrolysis process, biochar as a catalyst intensifies the removal of recalcitrant petroleum hydrocarbons at the expense of liquid product yield. Concurrently, biochar as an adsorbent can inhibit the release of micromolecular gaseous pollutants (e.g. HCN, H2S, and HCl) and stabilize heavy metals. Due to the assistance of biochar, pyrolysis reactions of OS are more likely to occur and require a lower temperature to achieve the same situation. During the soil reclamation process, the obtained residue as a soil amendment can not only provide a carbon source and mineral nutrients but can also improve the abundance and diversity of microbial communities. Thus, it facilitates the plant germination and the secondary removal of petroleum hydrocarbons. The integrated strategy of BCP of OS and residue utilization for soil reclamation is a promising management strategy, which is expected to realize the coordinated and benign disposal of more than one waste.

Preliminary Study on The Bio-Oil Production from Multi Feed-Stock Biomass Waste via Fast Pyrolysis Process

Biomass is a good resource for renewable energy. Biomass can be converted into bio-fuel (bio-oil) through a catalytic fast pyrolysis process. Previous studies only used single feedstock biomass as raw material for bio-oil production. In this study, bio-oil production is based on a multi-feedstock biomass waste consisting of rice husk, sugar cane bagasse, and palm oil empty fruit bunch. The mixture of biomass waste as a raw material is expected to enhance the yield and quality of the bio-oil produced. This study aimed to investigate the bio-oil products obtained from catalytic pyrolysis of the biomass waste mixture. Mixture Design from Design Expert was used to study the effect of biomass composition on the bio-oil products. Each biomass, i.e., rice husk, sugar cane bagasse, and palm oil empty fruit bunch, was previously chopped and sieved into a uniform 60 mesh. The pyrolysis process was conducted at 500°C with an N2 flow rate of 3 L min-1. The mixture of biomass waste husks contains more phenolic compounds than single-feedstock. The chemical characterization also showed that the multi-feedstock bio-oil compound was dominated by aldehydes, esters, and phenolic compounds.

Sustainable valorization of waste keyboard keys via microwave assisted pyrolysis over Fe-Ni doped green catalyst towards clean fuel production

ABSTRACT The technological evolution of electronic equipment in the field of computers and household appliances, along with shorter life of most items, is creating a great concern for managing this waste stream. The main aim of the present investigation was to convert waste keyboard keys into high-quality pyrolysis oil using a microwave catalytic pyrolysis process. Iron (Fe), Nickel (Ni), were doped in different ratios on Biochar (BC) by wet impregnation method, and it was used as a green catalyst for clean fuel production. Initially, a non-catalytic pyrolysis process was conducted and found a maximum pyrolysis oil yield of 49.6 wt.%. Further, microwave catalytic pyrolysis was conducted with variable amount of metal loading and found that highest oil yield of 61.33 wt.% was achieved using 15%Fe-5%Ni/BC catalyst due to the presence of a higher quantity of iron. The produced pyrolysis oil at this condition consists of 45.07% single-ring compounds and reduced the undesirable polycyclic aromatic hydrocarbons (PAHs) in the pyrolysis oil. This work provides a pathway for preparing green catalysts and safe disposal of electrical and electronic plastic waste with better resource recovery.

Catalytic deoxygenation with SO42--Fe2O3/Al2O3 catalyst: Optimization by Taguchi method

This work investigates the optimization of reaction parameters with the Taguchi method for catalytic deoxygenation of waste cooking oil (WCO) as an alternative renewable fuel process. Commercial sulphated-ferric (II) oxide/alumina oxide catalyst has the potential as a deoxygenation catalyst due to its good physicochemical properties which enhance the removal of oxygenated species. The obtained pyrolysis oil analysed by GC-MS revealed the selectivity of the pyrolysis oil mostly in the range of light diesel and kerosene fraction. From an analysis of variance (ANOVA), temperature awarded the most significant impact (86.62%) in this catalytic deoxygenation as compared to three other parameters followed by reaction time > N2 flow > catalyst loading. From the GC-MS analysis, the maximum renewable diesel fraction of 49.66% was obtained at 400 °C, 1 wt% of catalyst, 90 min of reaction time and 20 cm3/min N2 flow. The predicted model by Taguchi in the present study validated by the experimental work shows a promising application in optimising the catalytic pyrolysis process for future use.

Moderate pressure boosts the aromatization activity of HZSM-5 zeolite during catalytic pyrolysis of lignocellulosic materials

Lignocellulose pyrolysis has been deeply investigated in the past years as a potential route for the production of advanced biofuels and biochemicals from residues and wastes. However, the effect of pressure has rarely been addressed in catalytic pyrolysis processes. Accordingly, the current work reports a comprehensive study on the pressure influence during the catalytic pyrolysis of different lignocellulosic materials (oak wood, cellulose, hemicellulose, and lignin) using nanocrystalline HZSM-5 zeolite as a catalyst and a downflow fixed-bed reactor. In thermal pyrolysis tests, pressure increase affects negatively the bio-oil* (organic components in the liquid products) since it reduces its yield in favor of the production of char and gases. However, in the case of the catalytic pyrolysis tests, working under moderate pressure (10 bar) has very positive effects on bio-oil upgrading, minimizing its oxygen concentration (< 10 wt.%) and sharply increasing the carbon yield of aromatic hydrocarbons, while the undesirable coke deposited on the catalyst surface can be even reduced. This finding denotes the occurrence of a remarkable synergistic effect between the pyrolysis pressure and the catalyst loading. These outstanding results are attributed to a more efficient activity of the zeolite under mild pressurization since both oxygenated species and light olefins are more strongly adsorbed over the catalyst surface, facilitating their subsequent transformation into aromatic hydrocarbons. The sharp enhancement of the deoxygenation and aromatization activity does not involve higher coke deposition over the zeolite surface, thus attenuating one of the major limitations of the lignocellulose catalytic pyrolysis process.