Pyrolysis Of Waste Cooking Oil Research Articles

Low temperature pyrolysis of waste cooking oil using marble waste for bio-jet fuel production

Limestone powder, a by-product of top-down marble processing, exhibited high thermal stability and functionality as catalysts for the low-temperature pyrolysis of waste cooking oil (WCO) into biofuel. The marble waste (MW) contains calcite, dolomite, and quartz composites (CaCO3/MgCO3/SiO2) as non-uniform microcrystallites. Pyrolysis at 380 °C in 1 h increased the hydrocarbon composition of biofuel and reduced carboxylic acid. The biofuel composition contains 80 % hydrocarbon within the jet fuel C8-16 ranges. MW reduced the carboxylic acid concentration from 49 % in catalyst-free pyrolysis to less than 4 %. The optimum condition was obtained at 3 % MW, yielding 43.55 % linear hydrocarbon, 11.1 % cyclic hydrocarbon, and 1.02 % aromatic compounds that satisfied the bio-jet fuel classification. The incorporation of varying percentages of marble waste demonstrates a significant enhancement in the cyclic compounds, elevating the yield from ∼3 % in catalyst-free pyrolysis to an impressive ∼35 %. The hydrocarbon yield is higher when using 3%MW > 1%MW > 6%MW > 9%MW. Dolomite and calcite mixture in MW catalyzed triglyceride conversion to hydrocarbon by adsorbing carbonate in triglycerides to drive C–O bond dissociation. These studies provide a roadmap for the utilization of abundant resources locally available in Indonesia to sustain local energy demand.

Lignosulfonate-Based Carbon-Supported Pellets Catalyst to Enhance Sustainable Biofuel Production from Waste Cooking Oil.

In this study, a cost-effective and stable heterogeneous acidic carbocatalyst (CZnLS950) derived from Na-lignosulfonate (LS), a side product of the paper industry, was employed to produce hydrocarbon fuels through the pyrolysis of waste cooking oil (WCO) and crude natural-oil extracted from sunflower seeds, aligning with the principles of the circular economy. To enhance its practicality in industrial settings, the catalyst was synthesized in pellet form, enabling easy separation from the biofuel produced during the reaction. CZnLS950 exhibited remarkable catalytic efficiency in the pyrolysis of WCO, resulting in a 71 wt. % liquid biofuel yield under mild conditions. This performance is attributed to the unique synthesis procedure of acidic carbocatalyst, which utilizes LS and nano ZnO (20 nm) to create a hierarchical pore structure with acidic properties (1.1 mmol of NH3 g-1). Stability and reusability of the carbocatalyst were evaluated, and the results showed excellent stability with small catalytic deactivation (~5 wt. %) after the fourth use. Attempts at distinct catalytic mechanisms for WCO and sunflower seeds crude natural-oil pyrolysis were provided to understand the processes involved in obtaining the two different biofuels produced. Overall, this study sets the stage for exploring Lignosulfonate-based materials to achieve renewable biofuel from recycling streams.

Pyrolysis of waste cooking oil to high-quality bio-oil: An acid-base coordination ZSM-5@CaO-SBA-15 micro-mesoporous composites catalyst

An acid-base coordination SM-5 @CaO-SBA-15 composite with micro-mesoporous structure was prepared for the first time by using zeolite ZSM-5 as the acid source and alkaline-earth metal as base source. The composite has been investigated for its structure, acidity-basicity and catalytic activity on the pyrolysis valorization of waste cooking oil (WCO) to high-quality bio-oil. The characterization results show that the structure and property of the composite are of the incorporation of secondary building unit characteristic of zeolite ZSM-5 into the mesoporous walls of the composite which gives rise to the thicker mesoporous walls and more strong acid-base sites. Under the optimal conditions, the bio-oil yield and total acid value can reach 65.8% and 12.40 mg KOH/g, respectively. Furthermore, the new catalyst is of better catalytic stability. This strategy could be used as a new general method for the preparation of catalysts for the reaction system with multifold large molecules.

Optimization and production of renewable fuels from waste cooking oil and low-density polyethylene: Evaluating fuel properties and techno-economic feasibility of diesel replacement

Pyrolysis of waste cooking oil (WCO) and plastics have caught the eye of contemporary researchers and industrialists, as valuable fuels can be produced from these wastes. However, process parameters such as feedstock blend ratio and temperature have to be optimized to obtain high-energy fuels at low-energy supply. Hence, this study aims to provide an insight into the optimization and techno-economic feasibility for the production of diesel-equivalent fuel from WCO and LDPE. A full-factorial design of experiments was delineated between six temperatures and seven feedstock blend ratios to compare oil yields. An optimum bio-oil yield of 65% was observed at 500 °C and 2:1 (WCO:LDPE) blend-ratio. Further, pyrolyzed WCO and equal blends of WCO and LDPE were tested for fuel properties, and these confirmed to Grade No. 2 and Grade No. 4 diesel–fuel as per ASTM standards respectively. A techno-economic analysis indicated a payback period of <14 months for both the fuels.

Production of bio-oil from waste cooking oil via microwave-assisted pyrolysis in the presence of waste eggshell CaO and HZSM-5: Process optimization and catalyst lifetime exploration

Preparing bio-oil from pyrolysis of waste cooking oil (WCO) has the potential to alleviate the energy crisis and turn waste into a useful resource. In this study, CaO made from waste eggshells (EGC), along with zeolite HZSM-5, were used as catalysts, and the process optimization and catalyst lifetime were investigated. Monocyclic aromatic hydrocarbons made up the majority of the bio-oil produced. EGC largely facilitated decarboxylation when the EGC/WCO ratio was less than 0.4. However, when the ratio increased above 0.4, EGC was able to promote deoxygenation of alcohols, ketones, and esters in addition to decarboxylation. The appropriate pyrolysis temperature of WCO was 450 °C, and the EGC/HZSM-5 (EGC/HZ) ratio was 1: 1. After four further trials using the ideal EGC/HZ catalytic pyrolysis conditions, the catalyst lost its catalytic activity. Coke deposition and the CaCO3 formation changed the porosity and alkalinity of EGC, resulting in a decrease in its activity. The capacity of HZSM-5 was also reduced by coke deposition. This study reveals the causes of the progressive decrease in catalyst activity during catalytic pyrolysis and allow the development of practical solutions to improve catalyst performance.

Catalytic pyrolysis of waste cooking oil for hydrogen-rich syngas production over bimetallic Fe-Ru/ZSM-5 catalyst

Waste cooking oil (WCO) energy development offers an effective method for producing renewable fuels, enabling simultaneous resource recovery and pollution reduction. This study aims to develop a novel bimetallic Fe(Ni)-Ru/ZSM-5 catalyst toward H2-rich syngas production from WCO. The results show that Fe-Ru/ZSM-5 produced a higher maximum H2 yield (84.05 μmol·gcat.−1·s−1) than did Ni-Ru/ZSM-5 (41.76 μmol·gcat.−1·s−1) when fed at a 50 L/min rate at an optimal temperature of 700 °C. Fe-Ru/ZSM-5 presented a more prolific microporous distribution, whose structure contributes to the diffusion of the short-chain hydrocarbon intermediate reactants to enhance hydrogen production. Fe(III) can help to improve the conversion ratio of benzene and the anti‑carbon deposition capability of the catalyst. The dealumination and oxidation decreases the stability of the catalyst and may lead to inactivation. Furthermore, this study discusses the mechanism of bimetallic-loaded catalysts combining noble metals with transition metals in WCO pyrolysis. The results point to effective new approaches to increase H2 production through the catalytic pyrolysis of WCO.

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.

Production of hydrocarbon-rich bio-oil from catalytic pyrolysis of waste cooking oil over nickel monoxide loaded corn cob-derived activated carbon

The bio-oil produced by the catalytic pyrolysis of waste cooking oil (WCO) has great potential to become a substitute for fossil fuels. However, the low yield and high oxygen content of pyrolysis oil result in low added value. The low-cost production of high-yield and high-quality hydrocarbon-rich pyrolysis oil remains challenging. To efficiently convert WCO to high quality hydrocarbon-rich pyrolysis oil, a nickel oxide loaded activated carbon catalyst (Ni/AC) was introduced in the ex-situ catalytic system. The catalytic pyrolysis results showed that the catalyst exhibited high deoxygenation activity and the hydrocarbon content in the bio-oil could reach up to 99%. The selectivity of total aromatic hydrocarbons and monocyclic aromatic hydrocarbons in liquid oil could reach 86.38% and 68.47%, respectively. By extracting hydrogen from hydrocarbon fragment, the NiO site facilitates dehydrogenation, resulting in a gaseous product with syngas (CO, H2) as the main component, with a maximum syngas concentration of 70%. The hydrogen produced is favorable for hydrogen transfer reactions and as a result promotes deoxygenation and hydrocarbon production. This study provides valuable insight into a low-cost, efficient, and high-value-added way to recover WCO. It will avoid the risk of environmental pollution caused by WCO and provide a reference for the sustainable use of waste.

Microwave-assisted pyrolysis of waste cooking oil for bio-based hydrocarbons over Chem-CaO@SiC catalyst

Bio-based hydrocarbons derived from biomass pyrolysis is an important supplement to the fossil resources. The inhomogeneous temperature of catalytic bed is one of the important reasons for catalyst deactivation. Chem-CaO@SiC catalyst was synthesized for the conversion of waste cooking oil (WCO) to bio-based hydrocarbons in this paper. Compared with the catalyst prepared from physical mixing, the catalyst prepared by chemical reaction was performed better in maintaining the bio-oil yield and increasing the relative content of hydrocarbons in bio-oil. Catalyst characterization showed that CaO was well supported on the SiC-powder surface. Then the effects of SiC-ball bed temperature and CaO loading rate on product yield and distribution were investigated. Also, the deoxygenation pathway was discussed. More polycyclic aromatics were produced when the SiC-ball bed temperature was 550 °C and above. And the composite catalyst could inhibit the formation of PAHs. The bio-oil yield increased and high heating value of gas products decreased with the decrease SiC-to-CaO ratio, and more energy from the WCO flowed into bio-oil. The catalyst remained 0.622 times of the initial activity after 5 cycles.

Synthesis of CaO from waste shells for microwave-assisted catalytic pyrolysis of waste cooking oil to produce aromatic-rich bio-oil

Energy shortage and environmental pollution have attracted long-term attention. In this study, CaO were prepared from waste eggshell (EGC), preserved egg shell (PEC), clam shell (CLC) and crab shell (CRC), which were then compared with commercial CaO (CMC) to catalyze microwave-assisted pyrolysis of waste cooking oil (WCO) for enrichment of aromatics in bio-oil. The characterization results indicated that EGC and CLC contained 95.54% and 95.61% CaO respectively, which were higher than that of CMC (95.11%), and the pore properties of EGC were the best. In addition, the effects of CaO type and catalytic mode on pyrolysis were studied. In CaO catalytic pyrolysis, CMC and CLC in-situ catalysis produced more aromatics than ex-situ catalysis, and PEC and CRC were more conducive to aromatics formation in ex-situ condition. EGC was conducive to produce benzene, toluene and xylene (BTX) both in in-situ (19.04%) and ex-situ (20.76%) catalytic pyrolysis. In CaO/HZSM-5 catalysis, the optimal dual catalytic mode for generating monocyclic aromatic hydrocarbons (MAHs) was Mode A (CaO separated from HZSM-5 for ex-situ catalysis), and EGC/HZSM-5 performed well in benzene, toluene and xylene (BTX) production.

Effect of Reaction Parameters on Catalytic Pyrolysis of Waste Cooking Oil for Production of Sustainable Biodiesel and Biojet by Functionalized Montmorillonite/Chitosan Nanocomposites.

The use of waste oils as pyrolysis feedstocks to manufacture high-grade biofuels has prompted researchers to focus on developing renewable energy to overcome the depletion of fossil fuel supplies and the global warming phenomena. Because of their high hydrogen and volatile matter concentration, waste oils are ideal raw materials for the production of biofuels. It is challenging to attain satisfactory results with conventional methods, such as transesterification, gasification, solvent extraction, and hydrotreating due to flaws such as high energy demand, long time, and high operating costs. Catalytic pyrolysis of waste edible oils was employed as a resource for the generation of biodiesel. The application of the catalytic cracking process has the potential to alleviate the existing situation. In this study of catalytic cracking conversion of waste cooking oil to produce different biofuels, grades were investigated using two heterogeneous catalysts. The catalysts were activated montmorillonite (PAMMT) clay and its modified form using a chitosan biopolymer (PAMMT-CH) nanocomposite. The catalysts were identified using infrared spectroscopy, X-ray diffraction patterns, transmittance electron microscopy images, surface area, and thermal stability. The catalysts were tested for their performances using different amounts (0.1–1% by weight) at a temperature assortment of 200–400 °C during a time range of 60–300 min. The experimental studies were carried out in a batch reactor. GC mass spectra were used to investigate the catalytic cracking products. Fractional distillation is used to separate the final products from various reaction conditions. The physicochemical properties of resulting biofuels were profiled by quantifying their densities, viscosities, specific gravities, pour points, flash and fire points, cetane numbers, carbon and ash residues, and sulfur contents. The optimum conditions of the yield product were 300 and 400 °C, catalyst weights of 0.7 and 0.8% w/v, and reaction times of 120 and 180 min concerning the (PAMMT) and (PAMMT-CH) nanocomposite, respectively. The determined properties were located within the limits of the specific standards of ASTM specifications. As a result, the PAMMT nanocomposite produced biofuel comparable to biodiesel according to ASTM specifications, while the PAMMT-CH nanocomposite produced biofuel comparable to biojet.

Pulse pyrolysis of waste cooking oil over CaO: Exploration of catalyst deactivation pathway based on feedstock characteristics

Pulse pyrolysis was carried out to realize real-time monitoring of CaO catalyst deactivation and regeneration in the catalytic pyrolysis of waste cooking oil (WCO) and free fatty acids (FFAs) based on the pyrolysis characteristics of feed stocks. The high unsaturation of the feedstock decreases the initial decomposition temperature and reduces the content of oxygen-containing compounds. CaO catalyst was completely deactivated after several times of pulse pyrolysis. During the pyrolysis of WCO, the catalytic activity of CaO did not recover after the pause of pulse pyrolysis. However, the catalytic activity all recovered during the pyrolysis of FFAs, but the rate of deactivation was accelerated. A large amount of Ca(OH)2 and CaCO3 were detected in the deactivated catalyst, and soluble coke was not detected. The research suggested that the change of crystal phases and agglomeration were the vital cause that impact the CaO catalyst stability.

Effect of oil blends derived from catalytic pyrolysis of waste cooking oil on diesel engine performance, emissions and combustion characteristics

The purpose of this study is to study the effect of pyrolysis oil from economical feedstock waste cooking oil on engine performance, emissions and combustion characteristics. Effect of potassium and sodium hydroxide catalysts concentrations of 0.5, 1, 3, 5, 7 and 10% by weight on the oil yield was investigated. NaOH catalyst achieved the highest oil yield of 70% wt. at concentration of 1% wt. Pyrolysis oil was mixed with diesel oil in volume percentages of 0, 20, 40, 60, 80 and 100%. Oil blends were tested in a diesel engine at variable loads and rated speed of 1500 rpm. The higher oil blend ratio decreased the thermal efficiency, NOx and CO emissions about diesel oil. Increase of oil percentage in the blends led to the increase of specific fuel consumption, smoke and HC emissions about diesel oil. The oil blend B100 achieved the maximum decreases in thermal efficiency, CO and NOx emission by 29, 45 and 65%, respectively about pure diesel. Also, pure pyrolysis oil B100 showed the maximum increases in specific fuel consumption, HC and smoke emissions by 28.3, 33 and 11%, respectively related to diesel oil. Pyrolysis WCO could be alternative fuels in diesel engines.

Diesel Engine Performance, Emissions and Combustion Characteristics of Biodiesel and Its Blends Derived from Catalytic Pyrolysis of Waste Cooking Oil

This paper first describes a slow catalytic pyrolysis process used for synthesizing biodiesel from waste cooking oil (WCO) as a feedstock. The influence of variations in the catalyst type (sodium hydroxide and potassium hydroxide), and catalyst concentration (0.5, 1.0, 3.0, 5.0, 7.0 and 10.0% by weight) on both the pyrolysis temperature range and biodiesel yield were investigated. The results suggested that sodium hydroxide (NaOH) was more effective than potassium hydroxide (KOH) as catalysts and that the highest yield (around 70 wt.%) was observed for a NaOH concentration of about 1 wt.% The resultant pyrolysis temperature range was also significantly lower for NaOH catalyst, thus suggesting overall lower energy consumption. Compared to conventional diesel, the synthesized biodiesel exhibited relatively similar physical properties and calorific value. The biodiesel was subsequently blended with diesel fuel in different blend ratios of 0, 20, 40, 60, 80 and 100% by volume of biodiesel and were later tested in a compression ignition engine. Brake thermal efficiency and specific fuel consumption were observed to be worse with biodiesel fuel blends particularly at higher engine load above 50%. However, NOx emission generally decreased with increasing blend ratio across all engine load, with greater reduction observed at higher engine load. Similar observation can also be concluded for CO emission. In contrast, lower hydrocarbon (HC) emission from the biodiesel fuel blends was only observed for blend ratios no higher than 40%. Particulate emission from the biodiesel fuel blends did not pose an issue given its comparable smoke opacity to diesel observed during the engine test. The in-cylinder peak pressures, temperature and heat release rate of biodiesel fuel blends were lower than diesel. Overall, biodiesel fuel blends exhibited shorter ignition delays when compared to diesel fuel.

Microwave-assisted pyrolysis of waste cooking oil for hydrocarbon bio-oil over metal oxides and HZSM-5 catalysts

Microwave-assisted pyrolysis of waste cooking oil is an environmentally friendly and economical method for obtaining benzene, toluene, ethylbenzene, and xylene (BTEX) which are important industrial chemicals. This study provides new routes to produce of BTEX and the utilization of waste cooking oil. The effect of catalytic temperatures (350 °C, 400 °C, 450 °C, 500 °C, and 550 °C), types of metal oxide (CoO, NiO, ZrO2, SrO, CeO2, and CaO), catalytic modes (ex-situ mixed catalysis, ex-situ separate catalysis, and in-situ separate catalysis), and ratio of HZSM-5 to metal oxide (HZSM-5 only, 4:1, 2:1, 1:1, 1:2, and CaO only) were studied. Results showed high catalytic temperature promoted the formation of monocyclic aromatic hydrocarbons at the cost of a decrease in bio-oil yield. But the concentration of BTEXS (benzene, toluene, ethylbenzene, xylene, and styrene) only increased from 256.58 mg/ml to 259.55 mg/ml with a temperature increase from 500 °C to 550 °C. Alkaline earth metal oxides (CaO, SrO) showed a significant deoxygenation capability during co-catalysis with HZSM-5. However, when CaO was applied under ex-situ mixed catalysis, the concentration of polycyclic aromatic hydrocarbons was up to 35.47%, which was much higher than 9.18% under HZSM-5 only. Also, the concentration of BTEXS decreased from 256.58 mg/ml (HZSM-5 only) to 167.54 mg/ml (HZSM-5 mixed with CaO). Further investigation of catalytic mode showed that ex-situ separate catalysis was more suitable for co-catalysis of alkaline earth metal oxides and HZSM-5. The concentration of BTEXS were both significantly higher than that of HZSM-5 only, which increased by 121.81 mg/ml for CaO and 108.52 mg/ml for SrO under ex-situ separate catalysis. Further study showed that the highest concentration of BTEXS was 702.20 mg/ml obtained when the ratio of HZSM-5 to CaO was 2:1. It was almost 2.8 times higher than HZSM-5 alone and 42.2 times higher than non-catalytic results.

Characterization and Application of Molten Slag as Catalyst in Pyrolysis of Waste Cooking Oil

Chemical and physical analysis was performed to identify the molten slag composition and its ability to be used as alternative catalyst in pyrolysis of waste cooking oil. The implementation such type of catalytic material could be useful in reducing the process cost. To increase the efficiency (increase the active site) of molten slag, it was modified by acid washing that resulted in an increase in the acidity from 159 to 1224 µmol/g. The results showed that the yield of bio-fuel was increased and the product selective to n-C15 upon the modification of molten slag by acid treatment. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Esterification, Distillation, and Chemical Characterization of Bio-Oil and Its Fractions

In a previous study, crude bio-oil (CBO) was obtained from fast pyrolysis of waste cooking oil (WCO) under different conditions, varying the temperature and the residence time of the process. The s...

Green Biofuel Production via Catalytic Pyrolysis of Waste Cooking Oil using Malaysian Dolomite Catalyst

Malaysian Dolomite has shown potential deoxygenation catalyst due to high capacity in removing oxygen compound and produce high quality of biofuel with desirable lighter hydrocarbon (C8-C24). The performance of this catalyst was compared with several commercial catalysts in catalytic pyrolysis of Waste Cooking Oil. Calcination at 900 °C in N2 produced catalyst with very high activity due to decomposition of CaMg(CO3)2 phase and formation of MgO-CaO phase. The liquid product showed similar chemical composition of biofuel in the range of gasoline, kerosene and diesel fuel. Furthermore, Malaysian Dolomite showed high reactivity with 76.51 % in total liquid hydrocarbon and the ability to convert the oxygenated compounds into CO2, CO, CH4, H2, hydrocarbon fuel gas, and H2O. Moreover, low acid value (33 mg KOH/g) and low aromatic hydrocarbon content were obtained in the biofuel. Thus, local calcined carbonated material has a potential to act as catalyst in converting waste cooking oil into biofuel.

Successive desilication and dealumination of HZSM-5 in catalytic conversion of waste cooking oil to produce aromatics

An integrated modified HZSM-5 was prepared by sodium hydroxide leaching and followed by hydrothermal process in series, and the co-modified zeolites were then used to conduct the catalytic fast pyrolysis of waste cooking oil to investigate whether an enhanced production of aromatics could be obtained. X-ray diffraction, N2 adsorption–desorption, TEM and NH3-TPD were utilized to characterize the modified zeolites. Experimental results indicated that the crystal structure of HZSM-5 was damaged as alkali treatment time was beyond 4h, and a micro-mesopore hierarchical system was created inside the zeolites. Simultaneously, the strong acid sites decreased with the increment of modification time, while the weak acid sites performed an opposite inclination. The relative yields of aromatics and olefins presented deviation when alkali treatment time exceeded the specific limitation, and a moderate alkali treatment time of 4h was beneficial for promoting the yield of aromatics.

Effect of NiO/SiO2 on thermo-chemical conversion of waste cooking oil to hydrocarbons.

Increase in organic waste generation, dwindling nature of global oil reserves coupled with environmental challenges caused by waste oil disposal and burning of fossil fuels necessitated the need for alternative energy resources. Waste cooking oil obtained from the frying fish outlet was analyzed for its physicochemical properties using ASTM D-975 methods. Acid and Iodine values of the oil were 30.43 ± 0.32 mgKOH/g and 57.08 ± 0.43 mgI2/100 g respectively. Thermo-chemical conversion of the oil using NiO/SiO2 at different reaction conditions (pressure, temperature, and catalyst concentration) at a residence time of 3 h yielded 33.63% hydrocarbons. Hydro-catalytic pyrolysis of waste cooking oil at 400 °C, H2 pressure of 15 bars, and catalyst to oil ratio of 0.25 g/100 cm3 resulted in highest hydrocarbon yield (41.98%). The fuel properties of the product were: cetane number (71.16), high heating value (41.43 MJ/kg), kinematic viscosity (2.01 mm2/s), density (0.94 g/ml), saponification value (185.1 ± 3.96 mgKOH/g), and iodine value (20.57 ± 0.20 I2/100 g) respectively. These results show that the NiO/SiO2 could be a suitable catalyst for conversion of waste vegetable oil to hydrocarbons.