Catalytic deoxygenation of palm oil and its residue in green diesel production: A current technological review

Advancements in green diesel production for energy sustainability: a comprehensive bibliometric analysis

Green diesel as a second-generation biofuel has received enormous attention owing to the huge demand for renewable fuel for addressing the net zero target in 2050. This study examines the development of green diesel research through a bibliometric analysis. The state-of-the-art green diesel research is studied based upon 1285 documents (1153 articles and 132 reviews) retrieved from the Scopus database related to the used keywords. The analysis focused on three categories: publication outcomes, most cited papers, and research area identification. The VOSviewer and RStudio (bibliometrix) were applied to analyse the data, rationalized within the framework of author, affiliation, country, citation analysis, cross-dimensional keyword analysis, research streams, and research gaps. The general result of the study highlighted a continuous incline in article numbers classified into three stages: initiation, exploration, and elevation. Those articles were mainly published in bioenergy-themed journals, including Fuel, Energy & Fuels, and Renewable and Sustainable Energy Reviews. Taufiq-Yap Yun Hin is the highest contributor with 41 articles, and Fuel published 110 articles. The rapid growth of green diesel was also inferred by the extensive spread of research maps worldwide. Amid those swift developments, the state of the art on green diesel through bibliometric analysis is not available to the best of our knowledge as far. Subsequently, this review aims to display the state of the art, research gap, and future forecast of green diesel research.

Biomass as an alternative feedstock to oleochemicals

The huge demands for petrochemicals have led to a rapid increase in the production of these fossil-based derivatives. Biomass represents a promising feedstock for addressing the challenges related to petrochemicals in terms of the necessity to apply renewable sources and the need to decrease carbon emissions. Among the natural biomass products, most studies have attempted to upgrade natural oils owing to their promising advantages of worldwide availability, low-cost processing, and built-in functionality. This paper discusses the upgradation of natural oils to the most beneficial oleochemicals, including fatty acids, fatty alcohols, and fatty acid methyl esters. This review also covers the utility, physico-chemical properties, and the production processes for such materials. The interconnected reaction routes to produce oleochemicals and the affecting parameters (catalyst design, temperature, and pressure) are also elucidated. Furthermore, this article discusses the future perspective of oleochemicals based on their development in recent years.

Sustainable biofuel synthesis from non-edible oils: a mesoporous ZSM-5/Ni/Pt catalyst approach

This work examines the hydrodeoxygenation (HDO) activity of non-edible oils using a high surface area catalyst. The HDO activity was thoroughly examined and contrasted using the high surface area catalyst Ni/Pt-ZSM-5 as well as other supports like MCM-48 and H-beta. Ni/Pt bimetals supported on mesoporous ZSM-5 were created via reverse order impregnation to facilitate HDO of non-edible oils. Techniques such as XRD, FT-IR, BET, HR-TEM, HR-SEM, TPD, and TGA were used to characterize the produced catalysts. The synthesized catalysts considerably influenced the hydrodeoxygenation activities for the synthesis of lengthy chain hydrocarbons in a stainless-steel reactor with a high-pressure fixed bed between 300 and 375 °C under 10-40 bar hydrogen pressure. High levels of Ni/Pt-ZSM-5 acidity, textural, and H2 consumption qualities were discovered. Distributions of the products were also reviewed, along with comparisons of the structure-activity connections.

Selectivity of reaction pathways for green diesel production towards biojet fuel applications

Green diesel is the second generation biofuel with the same structure as fossil fuels (alkanes), allowing this biofuel to provide excellent fuel properties over biodiesel such as higher energy content and lower hazardous gas emission. Generally, green diesel can be produced through the deoxygenation/hydrogenation of natural oil and/or its derivatives at 200-400 °C and 1-10 MPa over supported metal catalysts. This process comprises of three reaction pathways: hydrodeoxygenation, decarboxylation, and decarbonylation. The extent to which these three different pathways are involved is strongly influenced by the catalyst, pressure, and temperature. Subsequently, the determination of catalyst and reaction condition plays a significant role owing to the feasibility of the process and the economic point of view. This article emphasizes the reaction pathway of green diesel production as well as the parameters influencing the predominant reaction route.

A comprehensive review on nanocatalysts and nanobiocatalysts for biodiesel production in Indonesia, Malaysia, Brazil and USA

Biodiesel is an alternative to fossil-derived diesel with similar properties and several environmental benefits. Biodiesel production using conventional catalysts such as homogeneous, heterogeneous, or enzymatic catalysts faces a problem regarding catalysts deactivation after repeated reaction cycles. Heterogeneous nanocatalysts and nanobiocatalysts (enzymes) have shown better advantages due to higher activity, recyclability, larger surface area, and improved active sites. Despite a large number of studies on this subject, there are still challenges regarding its stability, recyclability, and scale-up processes for biodiesel production. Therefore, the purpose of this study is to review current modifications and role of nanocatalysts and nanobiocatalysts and also to observe effect of various parameters on biodiesel production. Nanocatalysts and nanobiocatalysts demonstrate long-term stability due to strong Brønsted-Lewis acidity, larger active spots and better accessibility leading to enhancethe biodiesel production. Incorporation of metal supporting positively contributes to shorten the reaction time and enhance the longer reusability. Furthermore, proper operating parameters play a vital role to optimize the biodiesel productivity in the commercial scale process due to higher conversion, yield and selectivity with the lower process cost. This article also analyses the relationship between different types of feedstocks towards the quality and quantity of biodiesel production. Crude palm oil is convinced as the most prospective and promising feedstock due to massive production, low cost, and easily available. It also evaluates key factors and technologies for biodiesel production in Indonesia, Malaysia, Brazil, and the USA as the biggest biodiesel production supply.

Highly Selective Bio-hydrocarbon Production using Sidoarjo Mud Based-Catalysts in the Hydrocracking of Waste Palm Cooking Oil

In this work, Lapindo mud (LM) was used as catalyst support. This is because the Lapindo mud has a high SiO2 content of 45.33 %. This research aims to produce a hydrocracking catalyst based on Lapindo mud through impregnation of Ni and Pt metals as well as grafting amine groups. Ni and Pt metals impregnation using wet impregnation method followed by amine group grafting. The best catalyst in this study was NiPt-NH2/LM which contained Ni and Pt metals, surface area, and pore diameters of 1.68 wt.% and 0.4 wt.%, 6.59 m2/g, 15.51 nm, respectively. The effectiveness of the catalyst was tested against temperature and catalyst: feed ratio. The catalyst with the best activity and selectivity was tested for reusability 3 times through hydrocracking process. The yield of liquid products obtained in the hydrocracking process of WPO using NiPt-NH2/LM catalyst with the optimum temperature and the weight ratio of catalyst:feed at 550 oC was 79.4 wt. % which consists of hydrocarbon compound of 55.9 wt.%. The yield of liquid products obtained in the hydrocracking WPO using the used NiPt-BH2/LM catalyst was 28.4 wt.% which consists of hydrocarbon compound of 23.6 wt.%. Copyright © 2022 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). 

Facile Fabrication of SiO2/Zr Assisted with EDTA Complexed-Impregnation and Templated Methods for Crude Palm Oil to Biofuels Conversion via Catalytic Hydrocracking

Zr-containing SiO2 and their parent catalysts were fabricated with different methods using EDTA chelation and template-assist. The activity of the catalysts was explored in crude palm oil (CPO) hydrocracking, conducted under a continuous system micro-cylindrical reactor. The conversion features and the selectivity towards biofuel products were also examined. The physicochemical of catalysts, such as structure phase, functional groups, surface morphologies, acidity features, and particle size, were investigated. The study showed that the template method promoted the crystalline porous catalysts, whereas the chelate method initiated the non-porous structure. The catalysts’ acidity features of SiO2 and SiO2/Zr were affected by the preparation, which revealed that the EDTA chelate-assisted method provided higher acidity features compared with the template method. The CPO hydrocracking study showed that the SiO2/Zr-CEDTA provided the highest catalytic activity towards the hydrocracking process, with 87.37% of conversion attained with 66.29%.wt of liquid product. This catalyst exhibited selectivity towards bio-jet (36.88%), bio-diesel (31.43%), and bio-gasoline (26.80%). The reusability study revealed that the SiO2/Zr-CEDTA had better stability towards CPO conversion compared with SiO2/Zr-CEDTA, with a low decrease in catalyst performance at three consecutive runs.

Mechanism Insight into Catalytic Performance of Ni12P5 over Ni2P toward the Catalytic Deoxygenation of Butyric Acid

The Ni/P ratio of nickel phosphide has an important effect on the catalytic performance toward the deoxygenation of fatty acids to biofuel. The Ni12P5 cluster is preferred to model Ni12P5 catalyst with butyric acid as the reactant model of palmitic acid. The catalytic deoxygenation mechanism of butyric acid over Ni12P5 cluster has been theoretically investigated at GGA-PBE/DSPP, DNP level in dodecane solution. From butyric acid, the hydrodehydration is predominated to form n-butanal. Then, from n-butanal, low temperature benefits the hydroreduction to form butanol and then hydrodehydration to produce n-butane, whereas high temperature favors the direct decarbonylation to yield propane. n-Butane originates from n-butanol through hydrodehydration and not from n-butylene. Propane comes from n-butanal through decarbonylation and not from propanol and/or propylene. Additionally, CO stems from n-butanal through decarbonylation, whereas CO2 is ruled out from butyric acid through decarboxylation. Compared with Ni12P6 cluster, Ni12P5 cluster exhibits higher catalytic activity for the formation of butanal, n-butanol, and n-butane, while it displays lower catalytic activity toward the direct decarbonylation and dehydration to yield propylene. These results can be attributed to less negative charges of Ni-sites over Ni12P5 cluster, compared with Ni12P6 cluster.

Selective hydroconversion of coconut oil-derived lauric acid to alcohol and aliphatic alkane over MoO x -modified Ru catalysts under mild conditions

Molybdenum oxide-modified ruthenium on titanium oxide (Ru-(y)MoO _x /TiO₂; y is the loading amount of Mo) catalysts show high activity for the hydroconversion of carboxylic acids to the corresponding alcohols (fatty alcohols) and aliphatic alkanes (biofuels) in 2-propanol/water (4.0/1.0 v/v) solvent in a batch reactor under mild reaction conditions. Among the Ru-(y)MoO _x /TiO₂ catalysts tested, the Ru-(0.026)MoO _x /TiO₂ (Mo loading amount of 0.026 mmol g^-1) catalyst shows the highest yield of aliphatic n-alkanes from hydroconversion of coconut oil derived lauric acid and various aliphatic fatty acid C6-C18 precursors at 170-230 °C, 30-40 bar for 7-20 h. Over Ru-(0.026)MoO _x /TiO₂, as the best catalyst, the hydroconversion of lauric acid at lower reaction temperatures (130 ≥ T ≤ 150 °C) produced dodecane-1-ol and dodecyl dodecanoate as the result of further esterification of lauric acid and the corresponding alcohols. An increase in reaction temperature up to 230 °C significantly enhanced the degree of hydrodeoxygenation of lauric acid and produced n-dodecane with maximum yield (up to 80%) at 230 °C, H₂ 40 bar for 7 h. Notably, the reusability of the Ru-(0.026)MoO _x /TiO₂ catalyst is slightly limited by the aggregation of Ru nanoparticles and the collapse of the catalyst structure.

Hydrocracking optimization of palm oil to bio-gasoline and bio-aviation fuels using molybdenum nitride-bentonite catalyst

In this study, molybdenum nitride-bentonite was successfully employed for the reaction of hydrocracking of palm oil to produce a bio-gasoline and bio-aviation fuel. The prepared catalyst was characterized using XRD, FT-IR, and SEM-EDX. The acidity of the catalyst was determined using the pyridine gravimetric method. The result showed that the acidity of bentonite was increased after modification using molybdenum nitride. The hydrocracking study showed that the highest conversion and product fraction of bio-gasoline and bio-aviation fuel were exhibited by molybdenum nitride-bentonite 8 mEq g⁻¹. The catalyst was later used to optimize the hydrocracking process using RSM-CCD. The effects of the process variables such as temperature, contact time, and catalyst to feed ratio, on the response variables, such as conversion, oil, gas, and coke yield, were investigated. The analysis of variance showed that the proposed quadratic model was statistically significant with adequate precision to estimate the responses. The optimum conditions in the hydrocracking process were achieved at a temperature of 731.94 K, contact time of 0.12 h, and a catalyst to feed ratio of 0.12 w/v with a conversion of 78.33%, an oil yield of 50.32%, gas yield of 44.00% and coke yield of 5.73%. The RSM-CCD was demonstrated as a suitable method for estimating the hydrocracking process of palm oil using a MoN-bentonite catalyst due to its closeness to the optimal value of the expected yield. This study provided a potential catalyst of based on bentonite modified using molybdenum nitride for the hydrocracking of palm oil.

In this study, molybdenum nitride-bentonite was successfully employed for the reaction of hydrocracking of palm oil to produce a bio-gasoline and bio-aviation fuel.

Catalytic deoxygenation of palm oil over metal phosphides supported on palm fiber waste derived activated biochar for producing green diesel fuel

Palm oil conversion into green diesel by catalytic deoxygenation (DO) is one of the distinctive research topics in biorefinery towards a bio-circular-green economic model to reduce the greenhouse gas emissions. In this study, palm fiber waste was explored as an alternative precursor for the preparation of activated biochar as a support material. A new series of nickel phosphide (Ni–P) and iron phosphide (Fe–P) catalysts supported on palm fiber activated biochar (PFAC) was synthesized by wetness impregnation, and extensive characterization was performed by several techniques to understand the characteristics of the supported metal phosphide catalysts prior to palm oil deoxygenation for producing of green diesel (C₁₅–C₁₈ hydrocarbons). The PFAC support exhibited suitable physicochemical properties for catalyst preparation, such as high carbon content, and high porosity (S_BET of 1039.64 m² g⁻¹ with V_T of 0.572 cm³ g⁻¹). The high porosity of the catalyst support (PFAC) significantly promotes the metal phosphide nanoparticle dispersion. The DO of palm oil was tested in a trickle bed down flow reactor under hydrogen atmosphere. The outstanding catalytic performance of supported Ni–P and Fe–P catalysts provided an impressive liquid hydrocarbon yield between 63.37 and 79.65% with the highest green diesel selectivity of 62.64%. Decarbonylation (DCO) and decarboxylation (DCO₂) are the main pathways for the relative phosphide catalysts as presented by the high number of C_n−1 atoms (C₁₅ and C₁₇ hydrocarbons). In addition, metal phosphide/PFAC catalysts could achieve great potential application as a promising alternative catalyst for biofuel production via deoxygenation for large-scale operation owing to their excellent catalytic activity, simple preparation, and utilization of sustainable resources.

Palm oil deoxygenation over palm fiber activated biochar supported metal phosphide catalysts.