Deoxygenation Research Articles

Metal organic framework-derived advanced porous material supported catalysts for green diesel production from palm fatty acid distillate via deoxygenation pathways

Green diesel production from renewable non-edible feedstock through deoxygenation (DO) is a viable step to reduce dependency on petroleum-based fuel in the transportation sector. As such, the catalytic conversion of undiluted palm fatty acid distillate (PFAD) into paraffinic hydrocarbons through DO was explored using Ni-doped pyrolysed MIL-101 (MOF-Cr2O3). In this study, 4–25 wt% Ni/MOF-Cr2O3 catalysts were prepared through wet impregnation and calcined at 600 °C for 4 h under N2 flow, followed by reduction at 450 °C for 4 h under H2 flow. Catalytic DO was carried out within 280 °C–360 °C with a retention time of 1–5 h by using 1–7 wt.% of catalyst loading under continuous N2 flow. Results showed that 14Ni/MOF-Cr2O3 was the most effective catalyst for PFAD conversion into paraffinic hydrocarbons. About 93 % hydrocarbon yield with 91 % n-(C15+C17) selectivity was achieved using 3 wt% catalyst at 320 °C within 3 h. The exceptional catalytic activity was attributed to the synergistic correlation between catalyst properties, including finely dispersed Ni facilitated by a porous and high surface area support, and optimal presence of acid-base active sites on the catalyst. Preliminary studies showed that 14Ni/MOF-Cr2O3 displayed high stability in terms of catalytic activity and regeneration potential.

Effect of catalyst synthesis of bimetallic nickel-cobalt supported iron-based catalysts on converting palm kernel oil into bio-jet fuel via deoxygenation reaction.

Bimetallic nickel-cobalt supported magnetite catalyst has been synthesized using varies techniques such as hydrothermal reactor (R), wet-impregnation (W) and co-precipitation (C) approaches in order to study the effect of preparation methods on the catalytic efficiency of NiCo/Fe3O4 catalyst in transforming the PKO into bio-jet fuel via deoxygenation (DO) reaction. Noted, co-precipitation method rendered greater changes on textural morphological changes, with NiCo/Fe3O4 (C) specific surface area were 157 m2/g followed by Fe3O4 (25 m2/g), NiCo/Fe3O4 (W) (7 m2/g) and NiCo/Fe3O4 (R) (2 m2/g ), respectively. Indeed, NiCo/Fe3O4 (C) showed highest weak+strong acidic sites (15,038.1μmol/g). The efficiency of the DO followed NiCo/Fe3O4 (C) > NiCo/Fe3O4 (W) > NiCo/Fe3O4 (R) > Fe3O4, whereby the highest hydrocarbon yield was 90% and 21% is the lowest. Noteworthy to mention, all of the liquid product exhibited selectivity of over 90% towards the kerosene range. The deoxygenation reaction was optimized using the most effective catalyst, NiCo/Fe3O4 (C) catalyst, through the OVAT technique. The results showed that the optimal conditions were achieved at a temperature of 350 °C within 3 h by using 5 wt% of catalyst loading. The reusability and stability of the NiCo/Fe3O4 (C) catalyst were examined, revealing that the catalyst may be reused for up to 8 runs. During these runs, the catalyst achieved a hydrocarbon yield of up to 55% and a BJF selectivity of over 95%. The decrease in the yield and selectivity was attributed to coking, specifically in the form of graphitic carbon.

Effect of various silica-supported nickel catalyst on the production of bio-hydrocarbons from oleic acid

The conversion of fatty acids into bio-hydrocarbons can be carried out through a deoxygenation (DO) reaction. Catalytic deoxygenation of fatty acids can occur through three reaction pathways: decarbonylation, decarboxylation, and hydrodeoxygenation. In this study, three kinds of silica were prepared: (i) silica obtained from the rice husk ash (RHA); (ii) synthetic mesoporous silica SBA-16; and (iii) commercial silica. All prepared silica was used as supported nickel (Ni) catalyst for bio-hydrocarbon production through DO reaction of oleic acid. The objective of this study was to investigate the effect of variations of silica on the reaction pathway and final products composition of DO reaction of oleic acid. The catalysts were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), surface area analysis, and NH3-temperature-programme desorption. Based on XRF and XRD analysis results, it can be concluded that nickel was successfully impregnated into all silica. All samples of catalysts were used in a reaction carried out at temperature of 285 °C under a pressure of 40 bar H2 for 2h. The results showed that all catalysts were able to convert oleic acid to bio-hydrocarbon with differences in products composition. The highest oleic acid conversion of 98.25% was achieved with Ni/RHA catalyst but the obtained liquid products was the lowest among other catalysts. It is found that this phenomenon was closely related to the acidity properties of the catalyst.

Deoxygenation of waste sludge palm oil into hydrocarbon rich fuel over carbon-supported bimetallic tungsten-lanthanum catalyst

Activated carbon (AC) supported catalysts have been extensively applied as deoxygenation (DO) catalysts. However, the details of in situ experimental investigations that relevant to this catalyst are limited. Hereby, we present a series of operando/in situ spectroscopic experiments for DO of waste sludge palm oil (WSPO) by using atomically dispersed La-W bimetallic supported AC catalysts (La-W/AC) with well-defined structures. The La(5%)-W(2%)/AC catalyst prepared through co-precipitation (CP) process rendered high surface area (741 m2/g) and catalyst’s acidity (13319.16 µmol/g). Besides, the catalyst demonstrated a superior catalytic performance of DO reactivity under optimal reaction conditions of 0.5 % catalyst loading (CL), a one hour reaction time (Rt), and 250 °C reaction temperature (RT), achieving 98 % WSPO conversion to green fuel turnover frequency (TOF) of 0.0153 s-1. The reusability of La(5%)-W(2%)/AC catalyst was positively active for eight runs of DO process with constant of conversion rate at > 87 %. In addition, DO mechanism was of WSPO model compound (palmitic acid) was conducted to gain the clearer insight of reaction pathway catalysed by La-W/C catalyst. In situ FTIR analysis confirms the presence of intermediates (e.g. n-heptadecane, n-pentadecane, n-nonane, n-tridecane, and trimethylcyclopentene) that attributed buy the acid site of the heteropoly acid support. Besides, in situ XAS spectroscopy consolidates the oxidation state of La and W, where the presence of metal centre, support and substrate were confirmed to reflect the occurrence of palmitic acid DO on atomically dispersed La and W active sites. Thus, the present findings identified several key product intermediates during DO process, as well as the stable-state of catalyst structure, which suggest that the atomically dispersed La(5%)-W(2%)/AC catalysed reactions follow an unconventional decarboxylation/decarbonylation reaction pathways with the activation of oxygen (O2) removing is rate limiting.

Wet torrefaction of biomass waste into levulinic acid and high-quality hydrochar using H-beta zeolite catalyst

Wet torrefaction (WT) is an effective pretreatment method of biomass waste for producing high-quality hydrochar and valuable liquid products. This study delves into how acid catalysts and reaction conditions in WT impact the resulting hydrochar's surface characteristics and elemental composition, as well as the distribution of liquid products. The focus is on utilizing wood cellulose pulp residue (WCPR) as the feedstock with H-Beta zeolite catalyst in a nitrogen-rich environment. The WT process involves a temperature range of 180–260 °C, and reaction durations spanning 15–60 min. The findings reveal that WT conditions, including the catalyst for WCPR, significantly influence the hydrochar's properties and liquid product distribution. With increasing temperature and reaction time, the hydrochar experiences changes, including increased carbon content and reduced oxygen content. The study identifies 260 °C and 30 min as the optimal temperature and time for levulinic acid production, achieving a remarkable selectivity of 62.8% with the H-Beta zeolite catalyst using H2O/WCPR = 10. Various properties of the resulting hydrochar are assessed, including higher heating values (HHVs), decarbonization (DC), dehydrogenation (DH), deoxygenation (DO), enhancement factor, carbon enrichment, surface area, pore diameter, weight loss as well as solid, carbon, hydrogen, and energy yields. The WT + Beta_220 sample, processed at 220 °C for 30 min, exhibited the highest HHV at 30.3 MJ/kg and carbon content at 78.9% in hydrochar compared to various biomass types, with an enhancement factor of 1.51 and carbon enrichment of 1.63, while the sequence of element removal during WT prioritized as DO > DH > DC. Furthermore, it is worth highlighting that the most significant weight loss, increasing from 17.0 to 60.7%, was observed under the same WT conditions. Lastly, a comprehensive reaction pathway is proposed to elucidate the WT of WCPR with the presence of H-Beta zeolite catalyst under these optimized conditions.

Evaluation of the Optimal Conditions for Oxygen-Rich and Oxygen-Lean Torrefaction of Forestry Byproduct as a Fuel

Wood biomass is an alternative to fossil fuels. However, biomass use has several limitations. Torrefaction, in which reduction conditions prevail to overcome these limitations, has been suggested. Here, torrefaction using different wood chips (Liriodendron tulipifera, Populus canadensis, Pinus rigida, and Pinus koraiensis) was conducted under oxygen-rich and oxygen-lean conditions to determine the effects of oxygen. Torrefaction was conducted at 230–310 °C for 1 h. A mass yield difference of 3.53–20.02% p (percentage point) was observed between oxygen-lean and oxygen-rich conditions. The calorific value increased by a maximum of 50.95% and 48.48% under oxygen-rich and oxygen-lean conditions, respectively. Decarbonization (DC), dehydrogenation (DH), and deoxygenation (DO) occurred in the following order because of dehydration and devolatilization during biomass torrefaction: DO > DH > DC. The calorific value of the torrefied biomass increased linearly with the extent of all three processes. The combustibility index and volatile ignitability were calculated based on proximate composition to suggest the optimal conditions for replacing anthracite and bituminous coal. This study provides suggestions for stable operation in a standard boiler design.

Catalytic Deoxygenation of Oleic Acid Over CoMo/Zeolite Catalyst for Green Diesel Production

Due to the presence of certain oxygenated species, green diesel from deoxygenation (DO) technology was developed to replace traditional biodiesel. In this study CoMo-based catalyst was supported on zeolite for deoxygenation reactions. The catalyst was prepared by the wet impregnation method and then calcinated under a 20 mL min-1 N2 flow rate for 4 hours at a temperature of 550○C. The prepared catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Thermo-Gravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM) analysis. The effect of zeolite on the removal of the different oxygenated functional groups was investigated in the deoxygenation of oleic acid over supported CoMo catalysts at 350°C and atmospheric pressure. The deoxygenated liquid products were characterized by Fourier-transform infrared spectroscopy (FTIR), Gas Chromatography-Mass Spectrometry (GC-MS), and Higher heating value (HHV). Based on the study results, CoMo/Zeolite is give 90.86% hydrocarbon yield for 2 hrs. at 350°C and 300 rpm. Overall, The CoMo/Zeolite showed good catalytic performance due to its good physicochemical properties.

Synergistic effect of bimetallic Fe-Ni supported on hexagonal mesoporous silica for production of hydrocarbon-like biofuels via deoxygenation under hydrogen-free condition

The need to explore a sustainable manner to produce hydrocarbon-like biofuel has attracted tremendous interest. A series of bimetallic catalysts comprised of Fe and Ni with different Ni loadings supported on hexagonal mesoporous silica (HMS) were synthesized for the production of hydrocarbon-like biofuel via deoxygenation (DO) reaction without the use of external hydrogen. The bimetallic 10Fe40Ni/HMS catalyst possesses a high conversion (96.1%) and selectivity towards C8-C20 hydrocarbon (91.8%) during the DO reaction. This is because the finely dispersed Fe and Ni consisting of NiO and NiFe2O4 demonstrate strong acidity along with higher amount of Brönsted-Lewis acid properties. The DO reaction of triglycerides with bimetallic Fe and Ni supported on HMS is a sustainable process to produce hydrocarbon biofuel.

Computational Evaluation of Potential Molecular Catalysts for Nitrous Oxide Decomposition.

Nitrous oxide (N2O) is a potent greenhouse gas (GHG) with limited use as a mild anesthetic and underdeveloped reactivity. Nitrous oxide splitting (decomposition) is critical to its mitigation as a GHG. Although heterogeneous catalysts for N2O decomposition have been developed, highly efficient, long-lived solid catalysts are still needed, and the details of the catalytic pathways are not well understood. Reported herein is a computational evaluation of three potential molecular (homogeneous) catalysts for N2O splitting, which could aid in the development of more active and robust catalysts and provide deeper mechanistic insights: one Cu(I)-based, [(CF3O)4Al]Cu (A-1), and two Ru(III)-based, Cl(POR)Ru (B-1) and (NTA)Ru (C-1) (POR = porphyrin, NTA = nitrilotriacetate). The structures and energetic viability of potential intermediates and key transition states are evaluated according to a two-stage reaction pathway: (A) deoxygenation (DO), during which a metal-N2O complex undergoes N-O bond cleavage to produce N2 and a metal-oxo species and (B) (di)oxygen evolution (OER), in which the metal-oxo species dimerizes to a dimetal-peroxo complex, followed by conversion to a metal-dioxygen species from which dioxygen dissociates. For the (F-L)Cu(I) activator (A-1), deoxygenation of N2O is facilitated by an O-bound (F-L)Cu-O-N2 or better by a bimetallic N,O-bonded, (F-L)Cu-NNO-Cu(F-L) complex; the resulting copper-oxyl (F-L)Cu-O is converted exergonically to (F-L)Cu-(η2,η2-O2)-Cu(F-L), which leads to dioxygen species (F-L)Cu(η2-O2), that favorably dissociates O2. Key features of the DO/OER process for (POR)ClRu (B-1) include endergonic N2O coordination, facile N2 evolution from LR'u-N2O-RuL to Cl(POR)RuO, moderate barrier coupling of Cl(POR)RuO to peroxo Cl(POR)Ru(O2)Ru(POR)Cl, and eventual O2 dissociation from Cl(POR)Ru(η1-O2), which is nearly thermoneutral. N2O decomposition promoted by (NTA)Ru(III) (C-1) can proceed with exergonic N2O coordination, facile N2 dissociation from (NTA)Ru-ON2 or (NTA)Ru-N2O-Ru(NTA) to form (NTA)Ru-O; dimerization of the (NTA)Ru-oxo species is facile to produce (NTA)Ru-O-O-Ru(NTA), and subsequent OE from the peroxo species is moderately endergonic. Considering the overall energetics, (F-L)Cu and Cl(POR)Ru derivatives are deemed the best candidates for promoting facile N2O decomposition.

EFFECT OF CATALYST PROPERTIES ON THE DEOXYGENATION REACTION OF VEGETABLE OIL AND MODEL COMPOUND TO PRODUCE DIESEL RANGE HYDROCARBON FUELS: A REVIEW

The concern associated with the depletion of fossil fuel energy has opened up windows of opportunity for researchers to develop potential energy from renewable resources. The renewable green diesel with diesel range hydrocarbon structure has gained increasing popularity by removing oxygen molecule via direct or hydrodeoxygenation (HDO) and indirect or deoxygenation (DO) reaction. The catalyst design is an important key to achieve the high quality of diesel range hydrocarbon fuels. The different catalyst properties effect to the distribution of deoxygenated liquid product, the catalytic activity and coke formation during the reaction process. The interaction between metal and support catalyst causes electron transfer to give the synestistic effect. The acidity and basicity play important role in C-C and C-O breaking bond in triglyceride and prevent the coke formation. The pore structure and pore size catalyst provide the accessibility of active sites alleviates the diffusion limitation of reactants/ products.

Selective Deoxygenation of Sludge Palm Oil into Diesel Range Fuel over Mn-Mo Supported on Activated Carbon Catalyst

Originating from deoxygenation (DO) technology, green diesel was innovated in order to act as a substitute for biodiesel, which contains unstable fatty acid alkyl ester owing to the existence of oxygenated species. Green diesel was manufactured following a process of catalytic DO of sludge palm oil (SPO). An engineered Mn(0.5%)-Mo(0.5%)/AC catalyst was employed in a hydrogen-free atmosphere. The influence of Manganese (Mn) species (0.1–1 wt.%) on DO reactivity and the dissemination of the product were examined. The Mn(0.5%)-Mo(0.5%)/AC formulation gave rise to a superior harvest of approximately 89% liquid hydrocarbons; a higher proportion of diesel fraction selectivity n-(C15+C17) was obtained in the region of 93%. Where acid and basic active sites were present on the Mn(0.5%)-Mo(0.5%)/AC catalyst, decarboxylation and decarbonylation reaction mechanisms of SPO to DO were enhanced. Evidence of the high degree of stability of the Mn(0.5%)-Mo(0.5%)/AC catalyst during five continuous runs was presented, which, in mild reaction conditions, gave rise to a consistent hydrocarbon harvest of >72% and >94% selectivity for n-(C15+C17).

Evaluation and optimal design of a high stability hydrothermal deoxygenation process for production of green diesel fuel via deoxygenation of waste cooking oil

The environmental impacts of waste cooking oil (WCO) can be profoundly serious when it is not handled properly. Instead of discarding leftover cooking oil as waste, recent technological advancements have made it possible to use WCO as a sustainable feedstock for biofuels production, while also addressing the disposal issue. This work developed an efficient and high stability hydrothermal WCO transformation process into green diesel fuel. In the present work, a homemade environmentally benign activated carbon was prepared from a bio-sourced precursor and impregnated with a Pd precursor. A set of experiments were conducted at 300 °C–350 °C, 40 and 50 bar, and times up to 240 min to evaluate the performance of Pd/AC catalysts against deoxygenation (DO) and deactivation reactions. The results showed a substantial enhancement of the activity and stability of the coated Pd/AC catalyst versus the uncoated one. Also, the green diesel fuel possesses an outstanding higher heating value of 46 kJ/mol. Based on experiments, the best kinetic model for the DO process was developed. The optimum kinetic parameters were obtained by the optimization approach. For a wide variety of operating conditions, the projected product conversion demonstrated satisfactory agreement with the experimental results, with absolute average errors of less than 8%.

Highly active iron-promoted hexagonal mesoporous silica (HMS) for deoxygenation of triglycerides to green hydrocarbon-like biofuel

The interest in the production of sustainable hydrocarbon-like biofuel is increasing due to the environmental issues such as global warming and uncertainty of crude oil prices. A series of Fe catalysts (5, 10, 40, and 100 wt% Fe) supported on the hexagonal mesoporous silica (HMS) were successfully prepared for the production of biofuel via deoxygenation (DO) reaction. In the DO reaction, the diesel range biofuel is produced in the absence of H2 and solvents. Interestingly, the 40 wt.%Fe/HMS catalyst exhibited the highest conversion and selectivity of 81.4 and 84.8%, respectively toward C8-C20 hydrocarbons-like biofuel at 380 °C for 2 h. This performance is closely related to the well-dispersed Fe in the hematite phase, along with the interaction between Si-OH and Fe-O bonds. The acidity, surface area, and pore size of Fe/HMS have improved the catalytic activity. This result demonstrates that the Fe/HMS catalyst is a potential DO catalyst for the production of renewable hydrocarbon-like biofuel.

Production of Biodiesel from Waste Cooking Oil via Deoxygenation Using Ni-Mo/Ac Catalyst

Waste cooking oil (WCO) from palm oil is one of the most prospective biodiesel feedstock when compared to other oil seeds. Thus, WCO has great potential as a green source of diesel fuel for engines in motor vehicles and machinery. This project aimed to study the potential of three randomly selected types of WCO, namely; sample A (used 1× once to fry an egg), sample B (used 3–5× to fry salted fish), and sample C (used repeatedly to fry banana fritter) for the production of green diesel fuel over Ni-Mo/AC (nickel and molybdenum oxides incorporated with activated carbon) catalyst through the deoxygenation (DO) process. The prepared catalyst was characterized through X-ray diffraction (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). The DO process was performed at 350 °C to remove oxygen from the WCO samples. The liquid products were analysed by gas chromatography-mass spectrometer (GC-MS) and gas chromatography-flame ionization detector (GC-FID), to measure the yields of straight-chain hydrocarbons and fractions in the range C8‒C20. Results showed that the highest n-(C8‒C20) hydrocarbon fractions were produced in the order of sample B (89.93%) > C (88.84%) > A (82.81%).

Performance and emission characteristic studies on CRDi diesel engine fuelled with jatropha green diesel

The Use of the fossil fuel power increments regular that leads towards the consumption of fossil fuel along with emissions from diesel or pressure ignition engine contributes development of disease on individuals, thus global government’s arrangements orders call for emissions decline. The expanding comprehension of the above made environmentally agreeable and monetary invaluable resource of green diesel gas become more alluring lately. As a rule, Biodiesel and bioethanol are acknowledged because of the reality planned sustainable transportation fuels. Fatty substances are formed related with the long and direct hydrocarbon spine having a decreased volume of oxygen when contrasted and sugar, starch, and biomass that is cellulosic. It truly is, thusly, thought to be the engaging biomass for assembling hydrocarbon biofuels. Pyrolysis, synergist breaking, and hydro de oxygenation (HDO) are achievable channels for assembling diesel-range hydrocarbons from fatty oils, regularly comprehended as ‘green diesel’. Among these methodology, HDO could be the usually acknowledged course attributable to the high return of green diesel. Also, this course is associated with negligible absence of unsaturated fat’s carbons as unpredictable hydrocarbons. This course further offers the probability of co-handling of fatty substances with raw petroleum parts inside the current hydrotreatment item. in the daily life utilizatation of the fossil fuel

Upgrading properties of biochar fuel derived from cassava rhizome via torrefaction: Effect of sweeping gas atmospheres and its economic feasibility

Torrefaction is a promising biomass thermal conversion technology to produce biochar due to its ease of operation and mild operating conditions. In this study, cassava rhizome (CR) was torrified under various sweeping gas types (nitrogen (N2), carbon dioxide (CO2), mixture gas (N2 + CO2)) and flow rates (50, 150, 250 mL/min) at 200–300 °C for 30 min. The experimental results show that fuel properties of CR were remarkably upgraded after torrefaction. Sweeping gas has less effect on fuel properties of torrified CR than torrefaction temperature. Torrefaction under CO2 atmosphere produced the biochar with minimum ash content. Torrefaction at 300 °C under 50 mL/min CO2 was recommended as the promising condition to produce biochar replacing lignite coal. Thermal properties and chemical functional groups of the derived biochar suggested that torrefaction process removed mainly oxygen and hydrogen contents which could be achieved through decarbonization (DC), dehydrogenation (DH), and deoxygenation (DO) pathways. Economic feasibility revealed that the torrefaction of CR is cost-advantage under the proposed condition.

Comparative study of transition metal-doped calcined Malaysian dolomite catalysts for WCO deoxygenation reaction

In the present work, nickel (Ni), zinc (Zn), copper (Cu), cobalt (Co) and iron (Fe) are tested as catalyst dopants on Malaysian dolomite calcined at T = 900 °C (CMD900). The physicochemical properties of all synthesised catalyst are investigated by X-ray diffraction, Brunauer–Emmett–Teller surface area, temperature-programmed desorption of carbon dioxide and scanning emission microscopy. The synthesised catalysts are tested on the basis of the deoxygenation (DO) reaction of waste cooking oil to produce liquid fuels under N2 atmosphere. The chemical composition of the liquid product is identified by gas chromatography–mass spectroscopy. The overall study suggests that Ni/CMD900 catalyst exhibits the highest performance with over 67.0% conversion and high selectivity (80.2%) with a high proportion of saturated linear hydrocarbons that corresponds to green diesel. Result indicates that Ni/CMD900 is a highly potential DO catalyst with 19.8% oxygenated compound, which is favourable for decarboxylation and/or decarboxylation predominates.

Synthesis and Characterizations of Nickel Supported on Activated Charcoal and its Application for Green Fuel Production

Waste cooking oil (WCO) that contained triglycerides and fatty acid derivatives can be transformed to green fuel that have similar properties to the fossil fuel. Hence, this study was focusing on the production of green fuel hydrocarbons from feedstock of waste cooking oil by deoxygenation process. The deoxygenation reaction of WCO was conducted using different loading of nickel (Ni) (5, 10, 15 and 20 % w/w) supported on commercial activated charcoal. Based on the catalytic deoxygenation (DO) reaction, the highest conversion of hydrocarbon was achieved when the reaction undergo using Ni20%AC as catalyst at 350°C for 3 hours under inert atmosphere. The present of the higher loading active metal showed high DO reaction by decarboxylation and decarbonylation pathways with high hydrocarbon yield of 83% and high selectivity of n-C15 and n-C17. DO reaction also favoured the optimum strength of acidity. This study revealed that Ni20%AC catalyst is a promising catalyst for the green fuel production in WCO.

Renewable diesel via solventless and hydrogen-free catalytic deoxygenation of palm fatty acid distillate

This work involved the utilization of a byproduct from the palm oil refining process as reaction feedstock in a solventless and hydrogen-free catalytic deoxygenation (DO) over NiO–ZnO catalyst in producing diesel-like hydrocarbons as advanced biofuels. The catalyst supporter was synthesized using coprecipitation methods to form highly crystalline meso-macrostructured ZnO particles. The catalyst support was wet-impregnated with different loadings (wt %) of NiO to prepare the NiO–ZnO catalyst. X-ray diffraction patterns verified the persistence of good crystallinity and phase purity of the support, with fine NiO crystallites of size 14–22 nm. Synthesized NiO–ZnO catalysts demonstrated Type IV isotherm with H3 hysteresis loop with mesoporous-macroporous properties. The Brønsted and Lewis acidic sites of NiO–ZnO offer a synergy effect between the active site and catalyst supporter. Both N2 adsorption isotherm and electron microscopy analysis revealed the increase of the crystallite size of the catalyst by increase the NiO loadings. The catalytic activity of the NiO–ZnO catalyst was tested in a semi-batch reactor at 350 °C for 2 h in N2 atmospheric. The oxygenated compounds of palm fatty acid distillate (PFAD) have been successfully removed to form linear hydrocarbons as green diesel compounds. The synergistic effect between NiO and ZnO significantly enhanced the catalytic activity for substrate DO. The hydrocarbons product yield reached 83.4%, with a diesel range (C11–C17) selectivity of 86.0%. The green diesel, which contains diesel-range hydrocarbons, is suitable as an alternative fuel product for vehicle engine usage. It is possible to be upscaled and compatible with the existed petrochemical refinery facilities. Hence, this is a promising work could be an economic potential and give value added to the palm oil byproduct sectors.

Mechanistic and thermodynamic insights into the deoxygenation of palm oils using Ni2P catalyst: A combined experimental and theoretical study

Deoxygenation (DX) is a key enhancement process for biomass-derived biofuel production. To understand the DX mechanism of palm oils, we performed experimental and computational studies to investigate the DX reaction of palmitic acid on Ni2P catalyst. Experimental characterization and catalytic testing demonstrated that the DX on unsupported (0 0 1)-Ni2P catalyst prefers the decarbonylation (DCO) pathway over the hydrodeoxygenation (HDO) pathway with the ratios between 2.17 and 4.13 to 1. Mechanistic study using density functional theory calculation revealed that the DX of butyric acid also prefers DCO over HDO pathway. Both experimental and computational results suggested that the decarboxylation (DCO2) pathway is unlikely. The computation results indicated that the rate-limiting step of HDO pathway is in the butanol to butane conversion (activation energy Ea = 1.99 eV), whereas that of the DCO pathway is found during the butanal to propane conversion (Ea = 1.52 eV). However, additional thermodynamic analysis accounting for hydrotreating reaction condition (H2 = 50 bars at 653 K) suggested that the rate-determining step for the DCO pathway is actually the hydrogenation of butyric acid. In addition, the thermodynamics analysis also suggests that increasing reaction temperature may increase selectivity of HDO pathway. The mechanistic insights gained from this study will be beneficial for the enhancement of DX process for biofuel production.