Degree Of Deoxygenation Research Articles

Reduction and structural modification of MoOx/γ-Al2O3 catalysts through acetic acid treatment for green diesel production from corn distiller’s oil

Enabling new environmentally-friendly resources for fuels and platform chemicals is crucial to fulfill our future energy demands while enhancing circularity. Corn distiller’s Oil (CDO) − as a coproduct of the ethanol industry, serves as a sustainable supply of carbon that may be converted into energy, fuels and specialty chemicals. A current challenge in using renewable oxygenated feedstocks is the high amount of coking and catalyst fouling that occurs. This study examined the hydrothermal deoxygenation of CDO into green diesel using molybdenum oxide (MoOx) catalysts in a continuous process without using any external hydrogen. The possibility of reduction and developing oxygen-deficient surfaces on molybdenum oxide (MoOx) catalysts through acetic acid treatment or adding ceria (CeO2) was investigated in order to enhance the acidity of catalysts as well as catalytic activity and stability required for the production of green diesel from CDO. Results showed that the acidity of these catalysts as measured by NH3 temperature programmed desorption (NH3-TPD) had a strong correlation between the degree of deoxygenation and catalyst stability. Acetic acid treatment of the 7.5 wt% MoO3/γ-Al2O3 catalyst reduced MoO3 to MoO3-x, increased the Mo5+ species from 8.7 % to 22 %, created Mo4+ species and increased the catalyst surface acidity in the range of low to moderate strength by approximately 17 %. The use of acetic acid-treated molybdenum oxide (Hac-7.5 wt% MoO3/γ-Al2O3) catalyst enabled nearly complete (99.9 %) deoxygenation of CDO and heavy hydrocarbons cracking to produce diesel-like fuels. A moderate increase in catalyst surface acidity by acetic acid treatment also increased the selectivity of diesel-like fuel through hydrocracking of long-chain hydrocarbons. This low-cost modification step of catalyst improvement is promising for industrial application. However, cracking of hydrocarbons generated amorphous coke (no graphitic coke was observed) on the catalyst surface, which required periodic removal by controlled calcination of the catalyst in presence of air for further use.

Upgrading of Pyrolysis Bio-Oil by Catalytic Hydrodeoxygenation, a Review Focused on Catalysts, Model Molecules, Deactivation, and Reaction Routes.

Biomass can be converted into energy/fuel by different techniques, such as pyrolysis, gasification, and others. In the case of pyrolysis, biomass can be converted into a crude bio-oil around 50-75% yield. However, the direct use of this crude bio-oil is impractical due to its high content of oxygenated compounds, which provide inferior properties compared to those of fossil-derived bio-oil, such as petroleum. Consequently, bio-oil needs to be upgraded by physical processes (filtration, emulsification, among others) and/or chemical processes (esterification, cracking, hydrodeoxygenation, among others). In contrast, hydrodeoxygenation (HDO) can effectively increase the calorific value and improve the acidity and viscosity of bio-oils through reaction pathways such as cracking, decarbonylation, decarboxylation, hydrocracking, hydrodeoxygenation, and hydrogenation, where catalysts play a crucial role. This article first focuses on the general aspects of biomass, subsequent bio-oil production, its properties, and the various methods of upgrading pyrolytic bio-oil to improve its calorific value, pH, viscosity, degree of deoxygenation (DOD), and other attributes. Secondly, particular emphasis is placed on the process of converting model molecules and bio-oil via HDO using catalysts based on nickel and nickel combined with other active elements. Through these phases, readers can gain a deeper understanding of the HDO process and the reaction mechanisms involved. Finally, the different equipment used to obtain an improved HDO product from bio-oil is discussed, providing valuable insights for the practical application of this reaction in pyrolysis bio-oil production.

Catalytic depolymerization and hydrodeoxygenation of lignin to high-density fuel precursors using Ni/Nb2O5 catalyst

Converting lignin into renewable fuels via hydrogenolysis is crucial for achieving carbon neutrality. Existing methods primarily produce monomers in the carbon range of 6–9, inadequate for sustainable aviation fuels requiring heavier components. This study introduces a Ni/Nb2O5 catalyst for catalytic transfer hydrogenolysis of organosolv birch lignin with isopropanol, predominantly resulting in dimers and trimers within carbon ranges of 8–16 and 16–30, comprising 24.7 % and 60.5 % of the lignin-oil, respectively. The catalyst's oxygen vacancies and acid sites facilitate efficient C-O and C-C bonds cleavage, preserving a highly aromatic structure with reduced O/C ratio, elevated H/C ratio, and decreased unsaturation. Characterization techniques confirm a significant 55.5 % deoxygenation degree of the lignin-oil, making it suitable for the synthesis of customized fuel across various carbon numbers. This approach offers a practical pathway for obtaining renewable heavier fuel components and precursors from lignin, significantly advancing sustainable fuel technologies.

Targeted preparation for hydrocarbons through catalytic hydrodeoxygenation of co-pyrolysis bio-oil using bimetal-loaded Nb2O5 catalyst

The co-pyrolysis of industrial enzymatic hydrolysis of lignin residue with waste plastic to produce bio-oil can increase resource utilization and reduce pollution. However, the high concentration of oxygenated compounds, particularly phenolic compounds, limits the large-scale application of crude bio-oil. Bimetallic-loaded bifunctional catalysts have been prepared by loading different transition metals and Ru onto Nb2O5. We explored their performances in crude co-pyrolysis bio-oil hydrodeoxygenation (HDO). Compared to other transition metals, the selectivities for aromatic hydrocarbons, phenolic compounds, and other oxygenated compounds in the upgraded oil obtained by the catalytic HDO of Ni and Ru bimetallic-loaded Nb2O5 (Ni-Ru@Nb2O5) was the lowest, whereas the aliphatic hydrocarbons selectivity was the highest. The selectivities for other oxygenated compounds, phenolic compounds, and aromatic hydrocarbons in the upgraded oil decreased as the Ni loading increased, whereas the aliphatic hydrocarbons selectivity increased. Ni-Ru@Nb2O5 catalyzed HDO of crude bio-oil showed a maximum selectivity of 86.30 % for hydrocarbons in the upgraded oil at a reaction time of 2 h and a reaction temperature of 280 °C. The degree of deoxygenation of upgraded oil reached 68.87 % under optimal conditions, and the molar ratio of H-to-C was increased from 1.31 (crude bio-oil) to 2.37 (upgraded oil). Ni-Ru@Nb2O5 is an effective catalyst method for the HDO of crude bio-oil.

Selective production of high-value fuel via catalytic upgrading of bio-oil over nitrogen-doped carbon-alumina hybrid supported cobalt catalysts

Bio-oil derived from biomass fast pyrolysis can be upgraded to gasoline and diesel alternatives by catalytic hydrodeoxygenation (HDO). Here, the novel nitrogen-doped carbon–alumina hybrid supported cobalt (Co/NCAn, n = 1, 2.5, 5) catalyst is established by a coagulation bath technique. The optimized Co/NCA2.5 catalyst presented 100 % conversion of guaiacol, high selectivity to cyclohexane (93.6 %), and extremely high deoxygenation degree (97.3 %), respectively. Therein, the formation of cyclohexanol was facilitated by stronger binding energy and greater charge transfer between Co and NC which was unraveled by density functional theory calculations. In addition, the appropriate amount of Lewis acid sites enhanced the cleavage of the C–O bond in cyclohexanol, finally resulting in a remarkable selectivity for cyclohexane. Finally, the Co/NCA2.5 catalyst also exhibited excellent selectivity (93.1 %) for high heating value hydrocarbon fuel in crude bio-oil HDO. This work provides a theoretical basis on N dopants collaborating alumina hybrid catalysts for efficient HDO reaction.

Catalytic conversion of chicken fats into fuel grade hydrocarbons

Fatty acid is considered as a renewable source for producing transportation fuel. As there is an ongoing price hike of diesel and kerosene as well as a lack of sustainable fuel to mitigate global climate change, the current study developed a one-step process of fuel grade hydrocarbons production from low-grade chicken fats (as a fatty acid source) using NiO/γ-Al2O3 catalysts. Results showed that straight-chain hydrocarbons were obtained through deoxygenation of chicken fats at different temperatures (350 to 400 °C) and reaction times (0.25 to 1 h). 65% liquid yield and 87% degree of deoxygenation were obtained at the optimum reaction conditions (400 °C and 1 h) using 5 wt%NiO/γ-Al2O3 catalyst, whereas the liquid product contains 18.7% C8 to C15 alkanes, 38.5% hexadecane, 39% heptadecane and 3.8% C18 to C20 alkanes. Liquid product has a similar high heating value (HHV) and density as a commercial fuel such as diesel. This work opens a new research window in the field of green energy to improve global energy security.

Effect of Ni/Al-MCM-41 Impregnation Method on Catalytic Deoxygenation of Reutealis Trisperma Oil

Deoxygenation of Reutealis trisperma oil into green diesel has been carried out using Ni/Al-MCM-41 catalyst. The Ni/Al-MCM-41 catalyst was prepared using the wetness impregnation and incipient wetness impregnation methods, hereinafter referred to as Ni/Al-MCM-41 (WI) and Ni/Al-MCM-41 (IWI). XRD and FTIR analysis shows a characteristic of amorphous phase for solid Al-MCM-41 catalyst. FTIR pyridine was used to assess the impact of the NiO impregnation technique on Lewis acid and Brønsted acidity. The acidity test showed that the Ni/Al-MCM-41 (WI) catalyst had the highest total acidity 0,227 mmol/g. The catalytic activity of Ni/Al-MCM-41 catalyst was examined in deoxygenation reaction of Reutealis trisperma oil under inert conditions for 4 hours. In comparison to Ni/Al-MCM-41(IWI) and Al-MCM-41 catalysts, the Ni/Al-MCM-41(WI) catalyst produced better results in the deoxygenation reaction of Reutealis trisperma oil with a selectivity of hydrocarbon compounds (C11-18) of 100% and a degree of deoxygenation of 92.77%.

Catalytic upgrading of lignin-derived bio-oils over ion-exchanged H-ZSM-5 and H-beta zeolites

H-ZSM-5 and H-Beta zeolites ion-exchanged with alkali (Na+ and K+) and alkaline-earth (Mg2+) metals have been explored for the catalytic fast pyrolysis of lignin. Incorporating these metals led to a significant change in the acidic properties of the parent zeolites turning into mostly Lewis-type acidity. Catalytic fast pyrolysis experiments of lignin were performed in a fixed bed reactor with ex-situ configuration operating at 550 °C (thermal zone) and 450 °C (catalytic zone), atmospheric pressure and under a nitrogen flow. Moreover, two catalysts to lignin mass ratios (C/L = 0.2 and 0.4) were studied. Compared with non-catalytic tests, the use of parent zeolites caused a decrease in the bio-oil* (water-free basis) yield due to enhanced production of gases, water, and the coke deposition on the catalyst. In addition, the quality of bio-oil* was improved since it presents a lower oxygen content regarding the thermal test. H-Beta zeolite showed a higher deoxygenation degree than H-ZSM-5, but the latter exhibited a higher share of light components in the bio-oil* that can be detected by GC-MS analyses. Both catalysts promoted the production of light oxygenates, aromatics, and oxygenated aromatics. Regarding the effect of the incorporation of metals, oxygenated aromatic compounds were the predominant family in the bio-oil* obtained with all ion-exchanged zeolites. Likewise, significant differences were observed among the catalysts regarding the main components of this family (alkylphenols, guaiacols, syringols, catechols, and methoxybenzenes), achieving guaiacols concentrations in bio-oil* near to 24 wt.% for NaH-ZSM-5 and KH-ZSM-5 catalysts, and alkylphenols concentrations close to 16 wt.% for MgH-Beta and KH-Beta zeolites.

Catalytic hydropyrolysis of lignin: Insights into the effect of Ni catalyst and hydrogen using ReaxFF molecular dynamics simulation

Catalytic hydropyrolysis (CHP) of lignin as an emerging technology provides an efficient way of utilizing waste resources and promoting the production of alternative fuels and valuable bio-based products. The reinforcement of selective catalysts and hydrogen facilitates the overall conversion process but the mechanism remains difficult to clarify due to the complex nature of the system. This work employs a ReaxFF reactive molecular dynamics simulation method to explore the CHP of lignin dimer DMPD and the reaction mechanism at the molecular level. The results suggest that the hydropyrolysis (HP) system achieves a deoxygenation degree of 12.0 % for liquid products and the incorporation of hydrogen into pyrolysis suppresses the production of CO while promoting H2O and CH4 generation. The introduction of the Ni catalyst in the CHP system results in a liquid product yield of 68.9 wt % at 2000 K with a higher deoxygenation degree of 14.6 % due to the participation of a large amount of •H radicals species dissociated on the catalyst surface. The CHP reactions remarkably promote the production of phenols such as guaiacol and catechol and catechol is more likely to generate from the dynamic evolution of reaction intermediates. The integrated system also improves the production of H2O and light hydrocarbons like CH4 and C2H6. The first-order kinetic model reveals that the average activation energies of C-C, C-H, C-O bonds, and DMPD in the CHP system are significantly reduced to 113.12, 55.79, 59.99, and 132.17 kJ/mol in contrast to HP. The results indicate that the CHP system is more favorable for producing desirable liquid products with lower energy barriers.

Upgrading the corn cob pyrolysis vapors by processing over catalysts based on aluminium slag and the assessment of the produced bio-oil

In this paper the processing of corn cob pyrolysis vapors (CCPV) over catalysts based on aluminium slag (AS) was studied as a new route to produce bio-oil with improved quality. The processing of the CCPV was performed in a lab-scale fixed bed reactor applying raw and modified aluminium slag as catalysts and also without catalyst and the resulted bio-oils were compared.The proportion of the oxygenated compounds in bio-oil phase obtained without catalyst was increased compared with bio-oil phase obtained with catalysts, in which the concentrations of the compounds free of oxygen or with low oxygen content was predominant.The degree of deoxygenation (DOD) for bio-oils produced catalytically after five consecutive processing/regeneration cycles was in the range of 59.38–64.02 %,depending on the catalyst used, the highest DOD of 64.02 % was obtained for the bio-oil produced with NaAS as catalyst. During the CCPV processing on the catalyst was deposited coke leading to a possible its deactivation.The deposited coke amount was determined, the catalyst was regenerated by coke combustion and then reused in the five cycles. It could be observed that after five cycles of processing the amount of deposited coke remained almost the same(in the range 0.051–0.085 g) which indicated a good regeneration and a stable behavior of the catalyst. As such, the CCPV processing with catalysts based on AS represents an economically attractive alternative to more expensive catalysts such as zeolites for production of bio-oil with good quality, which may be further processed in conventional refineries or directly applied as a renewable fuel.

Influence of Interstructural Bonds in Biomass on the Thermophysical Characteristics of Biochar Produced by Hydrothermal Carbonization and Torrefaction

The influence of the temperature of hydrothermal carbonization and torrefaction on the properties of biochar obtained from biomasses (peat and sawdust) and model mixtures of structural components (cellulose, hemicellulose, and lignin) prepared in percentage ratios corresponding to their amounts in real biomass was studied. It was found that the yield of biochar decreased with temperature in both of the processes, whereas the degree of deoxygenation, the amount of carbon in the biochar, and its calorific value increased. A comparison of biochars from biomass and model mixtures was carried out. An assumption on the screening effect of lignin in heat treatment, which reduced the degree of degradation of the structural components of biomasses, was made.

Marine nitrogen cycling dynamics under altering redox conditions: Insights from deposition of sapropels S1 and the ambiguous S2 in the Eastern Mediterranean Sea

The eastern Mediterranean Sea (EMS) sedimentary record is periodically interspersed with organic-rich ‘sapropel’ layers. Sapropels are characteristic of basin-wide anoxic events, triggered by precession-forced insolation maxima. Relatively subdued insolation maxima, however, are not always expressed as distinct sapropel events. The EMS sedimentary record is thus useful to investigate feedbacks between marine anoxia and the nitrogen (N) cycle and offers an analogue for modern deoxygenation and past oceanic anoxic events. To this end, we investigated a ∼68 kyr sedimentary record from the EMS containing the well-established sapropel S1 (deposited in two phases: S1a [∼10.5–8.5 ka BP] and S1b [∼7.8–6.1 ka BP]) and sediments timed to the ambiguous S2 sapropel (∼53 ka BP). We used lipid biomarkers of microorganisms to reconstruct key N-cycle components: (1) anaerobic ammonium oxidation (anammox) using ladderanes and a stereoisomer of bacteriohopanetetrol (BHT-x), (2) dinitrogen gas (N2) fixation using heterocyte glycolipids, and (3) nitrification by Thaumarchaeota using crenarchaeol. Additionally, benthic foraminifera and trace metals (U, Mo, Mn) were used to reconstruct redox conditions. During S1a, abundances of Thaumarchaeota increased, likely promoted by elevated high-nutrient freshwater discharge. At this time, a combination of phosphorus supply and intensified loss of bioavailable N via water column anammox, may have reinforced anoxia by favoring diatom-diazotroph associations. During S1b, anammox is equally intense. Yet, no positive feedback on N2-fixation is observed, likely because diazotrophs were phosphorus limited. Instead, anammox may have provided negative feedback on anoxia by quenching primary production. Ladderanes suggest additional episodes of anammox between ∼69 to 39 cal ka BP, corresponding to brief periods of water column deoxygenation. Anoxia likely occurred at the sediment–water interface in S2-timed sediments (53–51 cal ka BP). During these episodes, ladderanes co-occur with the later eluting BHT-34R stereoisomer. δ13CBHT-34R indicate an anammox source, potentially synthesized by marine sedimentary anammox bacteria. No corresponding increase in diatom-diazotroph associations is observed, likely due to the oligotrophic conditions and the limited effect of sedimentary anammox on N-availability in the euphotic zone. Our results highlight various modes of operation of the N-cycle at different degrees of deoxygenation, which depend amongst others on nutrient-availability and the niche-segregation of N-loss and N2-fixating microorganisms.

Gas-Phase Deoxygenation of Biomass Pyrolysis Tar Catalyzed by Rare Earth Metal Loaded Hβ Zeolite

Biomass pyrolysis tar (BPT) with a higher heating value of 24.23 MJ/kg was used as raw feed for the catalytic gas-phase deoxygenation (GDO) process using Hβ zeolite loaded with different amounts of active elements (Ce, La, and Nd). Acetone molecule was chosen as a model compound to test the activity of pure Hβ zeolite, 1 wt% Ce/Hβ zeolite, 5 wt% Ce/Hβ zeolite, 1 wt% La/Hβ zeolite, 5 wt% La/Hβ zeolite, 1 wt% Nd/Hβ zeolite, and 5 wt% Nd/Hβ zeolite at 400 °C and process time of 3 h. BPT characterization showed a wide range of oxygenated compounds with the main components including water: 0.71%, furfural: 5.85%, 4-ethylguaiacol: 2.14%, phenol: 13.63%, methylethyl ketone: 5.34%, cyclohexanone: 3.23%, isopropanol: 4.78%, ethanol: 3.67%, methanol: 3.13%, acetic acid: 41.06%, and acetone: 16.46%. BPT conversion using 1 wt% Ce/Hβ zeolite catalyst showed the highest values of degree of deoxygenation (DOD) (68%) and conversion (16% for phenol, 88% for acetic acid, and 38% for 4-ethlyguaiacol). Yields of water, liquid phase, and gas phase in the GDO reaction using 1%Ce/Hβ zeolite were 18.33%, 47.42%, and 34.25%, respectively. Alkyl-substituted phenols and aromatic hydrocarbons achieved the highest yields of 37.34% and 35.56%, respectively. The main interaction pathways for BPT-GDO are also proposed.

Rational design of Ni-MoO3–x catalyst towards efficient hydrodeoxygenation of lignin-derived bio-oil into naphthenes

Design of a robust catalyst with high activity but the low cost for the hydrodeoxygenation (HDO) of bio-oils is of great importance to bring the biorefinery concept into reality. In this study, density functional theory (DFT) calculation was adopted to analyze the optimal location of Ni on MoO3–x containing oxygen vacancy, and the corresponding result demonstrated that metallic Ni cluster located at the neighborhood of oxygen vacancies would significantly evoke HDO activity. Enlightened by DFT results, NiMoO4 was first hydrothermally synthesized and then employed to fabricate Ni-MoO3–x catalyst via a low-temperature reduction, where Ni escaped from NiMoO4 and was reduced to its metallic state. Such an evolution of Ni species also induced the formation of oxygen vacancies around metallic Ni cluster. In the HDO of p-cresol, Ni-MoO3–x exhibited high activity with a complete conversion and a methylcyclohexane selectivity of 99.4% at 150 °C. Moreover, the catalyst showed good versatility in catalyzing HDO of diverse lignin-derived oxygenates and lignin oil. 2D HSQC NMR, gas chromatograph and elemental analysis of the lignin oil demonstrated the high deoxygenation efficiency and saturation of the benzene ring over Ni-MoO3–x. In the upgrading of crude lignin oil, the deoxygenation degree was up to 99%, and the overall carbon yield of the naphthenes was as high as 69.4%. Importantly, the structures and carbon numbers of the naphthene products are similar to jet fuel-range cycloalkanes, which are expected to have a high density that can be blended into jet fuel to raise the range (or payload) of airplanes. This work demonstrates the feasibility for improving the targeted catalytic reactivity by rational tailoring the catalyst structure under the guidance of theoretical analysis, and provides an energy-efficient route for the upgrading of lignin crude oil into valuable naphthenes.

Investigation on in-situ deoxygenation performance of bio-oil model compound guaiacol over Ce-Fe/Al2O3 catalyst

The investigation of the low-cost deoxygenation of guaiacol (GUA, a model bio-oil compound) is of importance for upgrading bio-oil. At present, common sulfide catalysts for GUA deoxygenation reactions cause contamination of the liquid product, and noble metal catalysts are economically disadvantageous. In this study, four reduced Fe-based oxides with different Ce doping ratios were prepared and their effects on the in-situ deoxygenation performance of GUA in aqueous/methanol hydrogen donor solvents were explored. The results based on the deoxygenation degree, conversion degree, and higher heating value (HHV) of the products showed that the oxide catalyst with a Fe/Ce molar ratio of 2:1 in the methanol solvent performed very well. After selecting an excellent catalyst and a better hydrogen donor solvent, four factors (reaction temperature, reaction time, volume ratio of GUA dosage and methanol dosage, and the ratio of catalyst dosage at the bottom of the reactor to that at the top) in the deoxygenation degree of GUA were investigated using an orthogonal experimental method to further explore the performance of the catalyst. The results showed that the reaction temperature and time greatly influenced GUA deoxygenation. Under optimal experimental conditions, the deoxygenation degree and conversion degree of GUA could reach 34.36% and 92.56%, respectively, based on the relative peak area of gas chromatography–mass spectrometry, and the HHV of the liquid product was 32.27 MJ/kg. Although Fe/Ce catalysts mainly promote demethoxylation, demethylation, and methylation, the stability and quality of the liquid products were improved compared with GUA owing to the reduction in phenolic hydroxyl and ether content. The reduced catalyst in the process of GUA in-situ deoxygenation reactions in methanol maintained a steady performance, as revealed by X-ray diffraction and X-ray fluorescence.

Hydrodeoxygenation of Pyrolysis Oil in Supercritical Ethanol with Formic Acid as an In Situ Hydrogen Source over NiMoW Catalysts Supported on Different Materials

Hydrodeoxygenation (HDO) is one of the most promising approaches to upgrading pyrolysis oils, but this process normally operates over expensive noble metal catalysts (e.g., Ru/C, Pt/Al2O3) under high-pressure hydrogen gas, which raises processing costs and safety concerns. In this study, a wood-derived pyrolysis oil was upgraded in supercritical ethanol using formic acid as an in situ hydrogen source at 300 °C and 350 °C, over a series of nickel–molybdenum-tungsten (NiMoW) catalysts supported on different materials, including Al2O3, activated carbon, sawdust carbon, and multiwalled nanotubes (MWNTs). The upgrading was also conducted under hydrogen gas (an ex situ hydrogen source) for comparison. The upgrading process was evaluated by oil yield, degree of deoxygenation (DOD), and oil qualities. The NiMoW/MWNT catalyst showed the best HDO performance among all the catalysts tested at 350 °C, with 74.8% and 70.9% of oxygen in the raw pyrolysis oil removed under in situ and ex situ hydrogen source conditions, respectively, which is likely owing to the large pore size and volume of the MWNT support material, while the in situ hydrogen source outperformed the ex situ hydrogen source in terms of upgraded oil yields and qualities, regardless of the catalysts employed.

Catalytic HDO of pyrolysis oil in supercritical ethanol with CoMoP and CoMoW catalysts supported on different carbon materials using formic acid as in-situ hydrogen sources

The work investigated performances of several CoMoP and CoMoW catalysts supported on different carbon materials in catalytic hydrodeoxygenation (HDO) of pyrolysis oil in supercritical ethanol using formic acid as an in-situ hydrogen source. Among them, the CoMoP catalyst supported on ZnCl2 activated sawdust carbon (ASC-Zn) and the CoMoW catalyst supported on multi-walled carbon nanotubes (MWNTs) showed the best HDO performance at both 300 °C and 350 °C for 2 h, obtaining higher upgraded oil yield, lower oxygen contents of the upgraded oils, and higher degrees of deoxygenation (DOD). Whereas the stability tests with three HDO cycles showed that both catalysts were slightly deactivated likely by active metals leach-out or coke/carbon deposition on active sites of the catalysts.

Catalytic hydroconversion of HTL micro-algal bio-oil into biofuel over NiWS/Al2O3

The demand for energy worldwide and the environmental concerns are increasing over the years, and microalgae is a potential raw material for third-generation fuel. In this work, the Chlorella sorokiniana microalga was converted by hydrothermal liquefaction (HTL) into a bio-oil using a batch reactor at 300 °C, under 10 MPa, for 30 min. Then, the bio-oil was upgraded using a batch reactor at three temperatures (350 °C, 375 °C, and 400 °C) under 10 MPa (H2) over NiW/Al2O3 sulfided catalyst. The bio-oil and upgraded fractions were characterized by elemental analysis, GPC-RID/DAD, 13CNMR, Sim-Dis, and GC×GC–MS/FID to identify the bio-oil molecular composition and follow its evolution. The lipids in the initial biomass, composed mainly of C16 and C18 chains/triglycerides, were converted into C16 and C18 fatty acids during the HTL reaction, corresponding to 41 % of bio-oil. Then, during the upgrading stage, these carboxylic acids were converted into C15 to C18 n-alkanes through two routes: hydrogenation or decarboxylation/decarbonylation, which was favored by temperature increase. >60 % of upgraded bio-oil eluted on the diesel range, as observed by Sim-Dis. The higher heating value (HHV) increased from 36 MJ/kg in the HTL bio-oil to 47 MJ/kg in the oil upgraded at 400 °C, and the average molar mass decreased from 333 to 203 g/mol. Oxygen and nitrogen compounds such as phenols, phytosterols, pyrroles, indoles, carbazoles, and amides were identified and quantified. Some insights about sulfur compounds are also given. The degree of deoxygenation, denitrogenation and desulfurization was higher than 90 % after the upgrading stage at 400 °C. Nevertheless, heterocyclic nitrogen compounds remained in the upgraded biooil. Therefore, catalytic hydrotreatment is confirmed as a relevant technology for upgrading HTL micro-algal bio-oil. However, catalyst performances can be improved to reduce less reactive nitrogen components.

Production of upgraded fuel blend from fast pyrolysis bio-oil and organic solvent using a novel three-stage catalytic process and its combustion characteristics in a diesel engine

An interdisciplinary approach involving the production and engine testing of a fuel blend containing upgraded bio-oil and fossil-derived solvent has been investigated in this present study. First, a novel 3-stage process of solvent-assisted catalytic upgrading of fast pyrolysis bio-oil was used to obtain a fuel blend with nearly 18 vol% biofuel content. Upgrading reactions were carried out between 160 °C and 300 °C, with 10 bar hydrogen gas, using 5 wt% Pt/Al203 catalyst for each of the three stages, with the main conversion reactions occurring in the first stage. The upgrading process produced 21.8 wt% of hydrocarbon-rich biofuel on bio-oil basis, achieving a high degree of deoxygenation with only 0.19 wt% oxygen in the final product. This was followed by the study of its combustion and emission characteristics in a 3-cylinder diesel engine, using a 10 vol% biofuel content in kerosene. All relevant testing regimes for liquid fuels were carried out, with its combustion and emission characteristics showing superior or similar results to those of conventions kerosene and diesel. The tested biofuel blend showed 2 % increments in engine performance. Overall, this work represents a significant advancement in the production of green liquid hydrocarbon-rich fuels for transport and domestic uses.

Ce-Loaded HZSM-5 Composite for Catalytic Deoxygenation of Algal Hydrolyzed Oil into Hydrocarbons and Oxygenated Compounds.

Despite the extensive research into the catalytic uses of zeolite-based catalysts, these catalysts have a limited useful lifetime because of the deactivating effect of coke production. This study looks at the use of Cerium (Ce) loaded HZSM-5 zeolite catalysts in the hydrocarbon and oxygenated chemical conversion from Chlorella Vulgaris microalgae crude oil. Characterization of structure, morphology, and crystallinity was performed after the catalysts were manufactured using the impregnation technique. Soxhlet extraction was carried out to extract the crude oil of microalgae. Transesterification reaction was used to produce algal hydrolyzed oil (HO), and the resulting HO was put to use in a batch reactor at 300 °C, 1000 rpm, 7 bars of nitrogen pressure, a catalyst to the algal HO ratio of 15% (wt. %), and a retention time of 6 h. To determine which Ce-loaded HZSM-5 catalysts would be most effective in converting algal HO into non-oxygenated molecules (hydrocarbons), we conducted a series of tests. Liquid product characteristics were analyzed for elemental composition, higher heating value (HHV), atomic ratios of O/C and H/C, and degree of deoxygenation (DOD%). Results were categorized into three groups: product yield, chemical composition, and carbon number distribution. When Cerium was added to HZSM-5 zeolite at varying loading percentages, the zeolite's acid sites became more effective in facilitating the algal HO conversion. The results showed that 10%Ce/HZSM-5 had the greatest conversion of the algal HO, the yield of hydrocarbons, HHV, and DOD% (98.2%, 30%, 34.05 MJ/Kg, and 51.44%, respectively) among all the synthesized catalysts in this research. In conclusion, the physical changes seen in the textural characteristics may be attributed to Cerium-loading on the parent HZSM-5; nevertheless, there is no direct association between the physical features and the hydrocarbons yield (%). The primary impact of Cerium alteration of the parent HZSM-5 zeolite was to change the acidic sites required to boost the conversion (%) of the algal HO in the catalytic deoxygenation process, which in turn increased the hydrocarbons yield (%), which in turn increased the HHV and DOD%.