High Acid Number Research Articles

Synthesis, Characterization, and Optimization of Antimicrobial Biolubricant Derived from Ocimum lamiifolium and Lactic Acid

Optimal extraction parameters were determined, yielding 12.4% oil at 4.5 hours, with a particle size of 1.375 mm and a solute-to-solvent ratio of 0.28 w/v. The extracted oil exhibited high yield (15% moisture, 0.92 g/mL specific gravity), a volatile lubricant component (3%), a pH of 4.2-5.91, low ash (11.5%), high saponification value (19.7 g KOH/g) and moderate acid number (8.9 mg KOH/g), iodine value of 35.3 g/L, low viscosity (0.1160 Pa.s), and high diffusion capacity (95%). Chemical analysis using UV-Vis spectrophotometry was employed to identify the constituents present in the extract, while FTIR spectra indicated the presence of alcoholic and phenolic components, suggesting interactions with lactic acid. Through GC/MS analysis, a total of 32 phytochemicals were identified, with seven significant ones: Eugenol (Phenol), Isocaryophyllene, Elemicin (benzene), Hexadecanoic acid with methyl ester, Octadecanoic acid with methyl ester, Neophytadiene and Squalene. Evaluation against E. coli, B. subtilis, S. typhimurium, and S. aureus revealed the O. lamiifolium extract and biolubricants most active against S. aureus and E. coli, suggesting potential for superior antibacterial lubricants with this plant extract and lactic acid.

Theoretical and experimental investigation of the impact of oil functional groups on the performance of smart water in clay-rich sandstones

This research investigated the effect of ion concentration on the performance of low salinity water under different conditions. First, the effect of injection water composition on interparticle forces in quartz-kaolinite, kaolinite-kaolinite, and quartz-oil complexes was tested and modeled. The study used two oil samples, one with a high total acid number (TAN) and the other with a low TAN. The results illustrated that reducing the concentration of divalent ions to 10 mM resulted in the electric double layer (EDL) around the clay and quartz particles and the high TAN oil droplets, expanding and intensifying the repulsive forces. Next, the study investigated the effect of injection water composition and formation oil type on wettability and oil/water interfacial tension (IFT). The results were consistent with the modeling of interparticle forces. Reducing the divalent cation concentration to 10 mM led to IFT reduction and wettability alteration in high TAN oil, but low TAN oil reacted less to this change, with the contact angle and IFT remaining almost constant. Sandpack flooding experiments demonstrated that reducing the concentration of divalent cations incremented the recovery factor (RF) in the presence of high TAN oil. However, the RF increment was minimal for the low TAN oil sample. Finally, different low salinity water scenarios were injected into sandpacks containing migrating fines. By comparing the results of high TAN oil and low TAN oil samples, the study observed that fine migration was more effective than wettability alteration and IFT reduction mechanisms for increasing the RF of sandstone reservoirs.

A continuous synthesis method of hydroxymethyl phosphonates using the microfluidic reactor

Hydroxymethyl phosphonates (HPs) are important organic chemical raw materials and intermediates. HPs are generally synthesized by phosphite esters and formaldehyde using the conventional organic synthesis device. It shows the disadvantages of strong heat-release and more by-products for the reaction, and high acid number (AN), low yield and low purity for the product. We have designed a microfluidic reactor to synthesize HPs that can overcome above mentioned disadvantages. During the microfluidic reaction process, a series of reaction conditions can be controlled precisely. According to adopt the optimal reaction conditions, five HPs were obtained with low AN (＜0.15 mg KOH/g), high yield (＞94%) and high purity (＞99%). The designed microfluidic reactor can reduce labor cost, save equipment area, and cut down the amount of wastewater. The synthesis process can also realize continuous production and scale-up production with no amplification effect.

Hybrid low salinity water and surfactant process for enhancing heavy oil recovery

Combining low salinity water (LSW) with surfactants has an enormous potential for enhancing oil recovery processes. However, there is no consensus about the mechanisms involved, in addition to the fact that several studies have been conducted in model systems, while experiments with rocks and reservoir fluids are scarce. This study presents a core-flooding experiment of LSW injection, with and without surfactant, using the core and heavy oil samples obtained from a sandstone reservoir in southeastern Mexico. The effluents and the crude oil obtained at each stage were analyzed. The study was complemented by tomographic analysis. The results revealed that LSW injection and hybrid process with surfactants obtained an increase of 11.4 percentage points in recovery factor. Various phenomena were caused by LSW flooding, such as changes in wettability and pH, ion exchange, mineral dissolution, detachment of fines and modification of the hydrocarbon profile. In the surfactant flooding, the reduction of interfacial tension and alteration of wettability were the main mechanisms involved. The findings of this work also showed that the conditions believed to be necessary for enhanced oil recovery with LSW, such as the presence of kaolinite or high acid number oil, are not relevant.

Production of biodiesel from fat of secondary crab materials

Production of biodiesel from the fat-containing entrails of king crab is investigated. These secondary raw materials are massively disposed (released into the sea) after separation of limbs. Routine technologies of the biodiesel production from vegetable and fish oils are used. The fatty acid composition of the fat is analyzed and the acid and peroxide numbers are determined. A high content of PUFAs (42.5 %) is detected, including the omega-3 (30.6 %) and omega-6 (12.3 %) fatty acids. High acid number (5.5 mg KOH per g fat) and peroxide number (85.6 mmol of active oxygen per g fat) of the crab fat do not meet the requirements for edible fish oils. The biodiesel in the form of fatty acid ethyl esters was produced from the crab fat with three indicators (NaOH, KOH, and H2SO4). Reactions with alkali did not give positive results due to formation of large amounts of soap. The best yield of esters was obtained in the experiment with sulfuric acid: 52.2 g of biodiesel was produced from 50.0 g of fat. Mechanisms of the reaction are explained and mass balances of the process are presented. Kinematic viscosity, total contamination, and acid number of biodiesel (4.96 mm2/s, 8 mg/kg, 0.35 mg KOH/g, respectively) meet the requirements of the national standard GOST R 53605-2009 (EN 14214:2003).

Analysis of the Contribution of Petroleum Acid Components to the Viscosity of Heavy Oils with High TAN.

The viscosity of heavy oil hinders its cold production, posing a major challenge to its exploitation. The high viscosity of heavy oil can be attributed to the content of asphaltene. However, during the collection of heavy oil samples from various regions in China, we observed that heavy oils with high total acid number (TAN) but low asphaltene content also exhibit relatively high viscosity. Hence, the viscosity mechanism of high-acid crude oil, the influence of petroleum acid on heavy oil viscosity, should be investigated. In this study, Xinjiang Chunfeng heavy oil was selected for analysis, possessing a viscosity of 16,886 mPa·s at 50 °C and a high total acid number (TAN) of 17.72 mg KOH/g. Separation was performed on the deacidified oil and the acid component using an alkali-modified silica gel column. The viscosity changes of the deacidified oil and its blends with varying proportions of the acid component were determined, along with the viscosity changes of the deacidified oil and acid components in a toluene solution. The molecular composition was analyzed using a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). The findings indicated successful separation of petroleum acid from the heavy oil, the acid component yield being 16.65 wt %. Furthermore, the viscosity of the petroleum acid was significantly higher than that of the deacidified oil. The rate of viscosity change of the acid component in the toluene solvent exceeded that of the deacidified oil, and the viscosity of the deacidified oil notably increased upon the addition of acid. In conjunction with the viscosity data, it was observed that the deacidified oil exhibited the removal of O2 and O4 compounds, resulting in a 43.11% viscosity reduction at 30 °C compared with crude oil. Thus, the monoacid and diacid components considerably affected the viscosity of heavy oil.

Effect of liquid contaminants on tribological performance of greases

This study investigates the effects of liquid contamination factors, including water, cutting fluid, and anti-rust oil, on the tribological properties of two lithium-based greases. Results show that these factors increase the friction coefficients and wear behaviors of both Li_M and Li_S greases. Empirical equations establish a correlation between the concentrations of contaminants and the specific wear rate of greases, showing not only the quality of the greases, but also their capacity to withstand the effects of liquid contaminants. The presence of water or cutting fluid in the tested greases decreases the tribofilm thickness, which is attributed to the grease–water spray phenomenon on the steel ball surface outside the wear scar. Li_M grease, characterized by a high total acid number and water retention capacity, has less friction and higher wear resistance than Li_S grease, but in the presence of contaminants its behavior is similar, with a slight improvement in Li_S grease. Moreover, the addition of water to the greases significantly increases the level of vibrations. These findings provide fundamental information for the selection of greases to be used under wet performance conditions.

Greener approach for the separation of naphthenic acid from model oil using Pyrrolidinium-based amino acid ionic liquids

Four novel pyrrolidinium-based amino acid ionic liquids were synthesized and characterized. The physicochemical properties of these amino acid ionic liquids (AAILs), such as viscosity, density, thermal stability, and surface tension were investigated. These ionic liquids (ILs) were used as a green chemistry approach for the extraction of naphthenic acid from the model oil. The influence of amino acid anions on the de-acidification process was assessed by attaching prolinate, glycinate, alaninate and serinate. Extraction results show that very small amounts of ILs are sufficient to extract naphthenic acid from a model oil configuration with a high total acid number. The regeneration and reusability of the synthesized ILs have also been analysed in this work. Moreover, the antimicrobial activity assay was performed to ascertain the potential toxicological effect of the synthesized set on the aquatic system.

Biodiesel production from high free fatty acid byproduct of bioethanol production process

Biodiesel is a reliable and promising replacement of fossil diesel. It is stable, less toxic and can be produced from sustainable resources, including a variety of raw materials. Currently, the most widely used are vegetable oils (edible and nonedible), due to their availability. The present paper considers the potential of obtaining fatty acid ethyl esters (FAEE) from corn oil, which is a byproduct of bioethanol production process. The ultimate outcome would definitely increase the profitability of the initial bioethanol production process. The biodiesel production process was implemented in two steps, due to the high content of free fatty acids of the obtained corn oil. The first step includes an acid-catalyzed esterification process and the second step comprises an alkali-catalyzed transesterification process to receive FAEE. Two different catalysts (sulfuric acid and p-toluene sulfonic acid) were utilized and compared each other in the esterification process, in order to cope with high acid number of the raw material. A comprehensive qualitative and quantitative analysis of both feedstock and biodiesel was performed using gas chromatography-mass spectrometry method. The obtained biodiesel was characterized by a significantly lower cloud point compared to the feedstock and high acid number.

A New Logistically Simple Solution for Implementing Alkali-Surfactant-Polymer/Alkali-Cosolvent-Polymer in Difficult Environments: Evaluation of Concept with High Total Acid Number Viscous Crude Oil

Summary Research on alkali-assisted chemical enhanced oil recovery (EOR) technology [alkali-surfactant-polymer (ASP)/alkali-cosolvent-polymer (ACP)] with high total acid number (TAN) crude oils has led to developments with liquid organic alkalis and cosolvents (Southwick et al. 2020; Fortenberry et al. 2015; Schumi et al. 2019; Upamali et al. 2018). Both concepts afford potential significant cost reduction in field operations, but to date it has not been demonstrated that these two concepts can work together. Monoethanolamine (MEA) alkali and a wide variety of liquid cosolvents are evaluated with high TAN crude oil (1.5 mg KOH/g oil). Formulations are found that give ultralow interfacial tension (UL-IFT) at a specified injection salinity. Fine tuning the formulation to different injection salinities can be done by choosing alternate cosolvents (or a cosolvent blend). A formulation comprising 1% MEA and a novel high molecular weight (3152 g/gmol) cosolvent, 0.5% glycerin alkoxylate with 30 mol of propylene oxide and 35 mol of ethylene oxide (glycerin-30PO-35EO), gave UL-IFT in 21,000 total dissolved solids (TDS) injection brine and gave 100% oil recovery in Bentheimer sandstone with 3,500 ppm FP 3630Ss (SNF Flopaam 3630Sis partially hydrolyzed polyacrylamide) as mobility control agent. All oil was produced clean, no separation of emulsion was needed to measure oil recovery. Alkali consumption tests were also performed with a high-permeability reservoir sandstone. Results confirmed earlier data published with Boise outcrop sandstone (Southwick et al. 2020) showing low alkali consumption with MEA. On a mass basis, only 12% of the amount of MEA is consumed relative to the amount of sodium carbonate consumed. This reduces the logistical challenges of shipping chemicals to remote locations. MEA is also a low-viscosity liquid which further simplifies field handling.

VALORIZATION OF DATE KERNELS FOR THE PRODUCTION OF BIODIESEL

This work is part of the diversification of renewable energy sources, such as biomass for example. This research focuses on the recovery of date seeds which cannot be consumed by humans and are considered as waste. For this, the physicochemical and biochemical properties of these seeds were studied and determined. The results obtained allowed us to conclude that this waste product can be valorized for the production of biodiesel. Besides, the techniques adopted to achieve the best results in terms of quality were investigated as well. In addition, the process of extracting oils from date seeds was determined using the Soxhlet extraction procedure with a volatile solvent. The results obtained showed that the oil content of date seeds was estimated at around 4% to 5%, with a very high acid number (8.9776). This was achieved by means of the esterification and transesterification reactions, which allowed producing biodiesel. This method makes it possible to produce up to 91% of biodiesel with characteristics close to those reported in previous studies and recognized by international standards.

Conversion of fruit kernels of Algerian date palm (Phoenix dactylifera L.) into biodiesel

Today, renewable energies have become one of the most important concerns of the countries of the world as a result of the negative effects we have reached on the environment from our use of fossil fuels and the resulting emissions of toxic gases. It is no secret that the fields of renewable energies are very diverse, including those derived from biomass. Researchers in this field seek to diversify bioenergy sources from ethanol, biodiesel, and fuels. Biogas. Accordingly, we conducted this study using date kernel oil as a new source for biofuel extraction, and the results were as follows: oil content of 4 to 5 percent, with a very high acid number of 8.9776, which imposes on us make a reaction of esterification and transesterification. Biodiesel has a 91 percent yield and its properties are close to recognized standards compared to previous studies.

A Critical Review of Alkaline Flooding: Mechanism, Hybrid Flooding Methods, Laboratory Work, Pilot Projects, and Field Applications

Over time, the dependence on oil has increased to meet industrial and domestic needs. Enhanced oil recovery (EOR) techniques in this regard have captured immense growth as EOR is not only used to increase the oil recovery but also to augment the sweep efficiency. Several techniques over the past decades have been used to improve oil recovery with cost-effectiveness. Cost-effective alkaline flooding has been effective for those oil reservoirs with a high total acid number. In this review, the significance of alkaline flooding has been discussed in detail, as well as the features of alkaline flooding in comparison to other modes of flooding. This review entails (1) alkaline flooding, (2) hybrid modes of injection, (3) experimental work, (4) pilot projects, (5) screening criteria, and (6) field applications. The findings of this study can help increase the understanding of alkaline flooding and provide a holistic view of the hybrid modes of flooding.

INVESTIGATION OF SOYBEAN PROCESSING BY FORCING – EXTRACTION METHOD

The study of the influence of physicochemical parameters of different sorts of soybean on the extraction of oil in soybean processing, as were as determining the quality of soybean products – petal, meal and oil. Soybean seed samples of three sorts were selected for the study: Mriya, Skelya and Ukrainka, of different humidity and degree of contamination. The Perten DA 7250 infrared analyzer and physicochemical methods in accordance with DSTU were used to determine the quality indicators of soybean seeds. Skelya sort was noted as more oily (20.36%), and Ukrainka sort as more protein (38.49%), the mass fraction of fiber in the samples is from 5.9 to 6.5%. The scheme of soybean processing by the method of forcing – extraction with hexane at the enterprise of «Tavria Agroinvest» was used. Soybean oil is extracted according to the technological regime of the enterprise. After the process of extraction and distillation of the solvent in the evaporator tank, unrefined soybean oil and soybean meal are obtained. According to the scheme of the extraction process, the quality of the final product will depend on the degree of grinding of raw materials and the quality of the petal. Organoleptic and physicochemical parameters of unrefined soybean oil and soybean meal obtained at «Tavria Agroinvest» from three sorts of soybean seeds were determined. It is shown that from moist materials (18.5%) is obtained oil with higher acid and peroxide numbers. The iodine number and cloud point of soybean oil of this sample are also higher than those obtained for dry seeds. The quality indicators of soybean meal for the studied soybean seed sorts were obtained. Mass fraction of crude protein in terms of absolute dry matter is the largest for the Skelya sort and is 46.2%. Soybean meal sort Mriya is less purified from moisture and crude fat, and its high acid number can shorten the shelf life.

Risk assessment of different edible oils subjected to heat at different time intervals and analyzed by titrimetric and instrumental methods and biological estimation on Wistar albino rats

Oils and fats in the diet serve three functions in the human body: as an energy source, a structural component, and as important biological regulators. Lipid peroxidation may be accelerated by repeatedly heating soy oil. Unsaturated fatty acids that have been oxidised may play a role in the aetiology of a variety of diseases. The purpose of this study was to see if repeatedly heating edible oil had any negative consequences on illness development. In this investigation, four different edible oils were heated to their regular boiling point and then heated for another 3 hours at a 1hour interval. The heated samples were subjected to qualitative examination. After analysing the results, it was discovered that saponification values declined as continuous heating, i.e. 3 hours, was applied to all different oils, resulting in low saponification values when compared to 2 hours, 1 hour, and normal boiling point. Lower the saponification value, the more free fatty acids and triglycerides are produced, which may contribute to cardio vascular illness. The acid values grew as the heating progressed, according to the findings. A high acid number suggests that there is a lot of acid in the system. The values of iodine fell as the heating progressed, according to the results. The presence of saturated fatty acids is indicated by a low iodine value. Saturated fatty acids were detrimental to one's health. As the heating progressed, the peroxide levels grew. Deterioration is indicated by an increase in peroxide value. When compared to other oils, palm oil showed a high saponification value, acid value, peroxide value, and low iodine value. Total cholesterol, tri-glycerides, and glucose levels were higher in 3 hours heated oils than in 2 hours, 1 hour, and at normal boiling point in biological tests.

Heavy Oil Recovery by Alkaline-Cosolvent-Polymer Flood: A Multiscale Research Using Micromodels and Computed Tomography Imaging

Summary For reservoirs containing oil with a high total acid number, the alkali-cosolvent-polymer (ACP) flood can promote the formation of microemulsion rather than viscous macroemulsion and achieve good mobility control. The enhanced oil recovery (EOR) performance of ACP flood has been studied at core and reservoir scale in detail; however, the effect of ACP flood on residual oil still lacks enough research. In this paper, a micromodel with a single channel is used to clarify the dynamic effects of alkali-cosolvent (AC) and ACP solutions on the residual oil after waterflood. Based on this, medical computed tomography (Medical-CT) scan and microcomputed tomography (Micro-CT) scan are used in combination to visualize microscale flow and reveal the mechanisms of residual oil reduction during ACP flood. The heterogeneous core plugs containing two layers of different permeabilities are used for coreflood experiments to clarify the EOR performance of ACP flood in heterogeneous reservoirs. The oil saturation is monitored by Medical-CT. Then, two core samples are drilled in each core plug that is used in the coreflood experiment. The decrease of residual oil saturation caused by ACP flood is further quantified by Micro-CT imaging. Results show that ACP flood is 14.5% oil recovery higher than AC flood (68.9%) in relative high permeability layers (HPLs) and 17.9% higher than AC flood (26.3%) in relative low permeability layers (LPLs). Compared with AC flood, ACP flood shows a more uniform displacement front, which implies that the injected polymer effectively weakened the viscosity fingering. This is similar to the experimental results demonstrated visually in the micromodel experiments. ACP solution first generates an oil bank by the mobility ratio improvement to mobilize residual oil and then dissolve and emulsify residual oil under ultralow interfacial tension (IFT) conditions. Moreover, a method that can calculate the ratio of oil/water distribution in each pore is developed to establish the relationship between the residual oil saturation of each pore and its pore size, and concluded that they follow the power-law correlation.

Metal Rod Surfaces after Exposure to Used Cooking Oils

Used cooking oils (UCOs) have a high potential as renewable fuels for the maritime shipping industry. However, their corrosiveness during storage and usage are some of the concerns yet to be investigated for addressing compatibility issues. Thus, the corrosion of steels and copper exposed to the UCOs was studied through the immersion of metal rods for different periods. The changes on the rod surfaces were analyzed with a scanning electron microscope (SEM). After the immersion, the copper concentration dissolved in the bio-oils was measured using inductively coupled plasma-optical emission spectrometry (ICP-OES). The free fatty acids and glycerides were analyzed using gas chromatography with flame ionization detection (GC-FID). The acid number (AN), water concentration, as well as density and kinematic viscosity of the bio-oils were determined with standard methods. The UCOs with the highest water content were corrosive, while the oils with lower water concentrations but higher ANs induced lower corrosion. After mixing two different UCOs, the metal corrosion decreased with an increasing concentration of the oil with lower corrosive properties. The lower corrosion properties were most likely due to the monounsaturated fatty acids, e.g., oleic acid in oils. These acids formed a barrier layer on the rod surfaces, thereby inhibiting the permeation of oxygen and water to the surface. Even adding 0.025 wt% of tert-butylamine decreased the corrosivity of UCO against polished steel rod. The results suggested that mixing several oil batches and adding a suitable inhibitor reduces the potential corrosive properties of UCOs.

The Effectiveness of Ni/Ce/Al<sub>2</sub>O<sub>3</sub> Catalyst in the Extraction of Naphthenic Acids from Acidic Crude Oil

Processing of petroleum crude oil with high total acid number (TAN) lead to corrosion problems in oil refinery equipment, storage, facilities and even reduces the performances of the oil. The purpose of this study is to overcome the corrosion problem in oil refinery by reducing the TAN in the oil to less than 1 mgKOH/g. A 2-methylimidazole in ethanol with the aid of Ni/Ce (10:90)/Al2O3 catalyst through the catalytic deacidification technique. The catalyst was prepared by using Incipient Wetness Impregnation (IWI) methods on alumina beads as catalyst support and calcined at 800°C, 900°C and 1000°C. Ni/Ce (10:90)/Al2O3 catalyst was characterized by using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction Spectroscopy (XRD) and Brunauer-Emmett-Teller (BET) to study physicochemical properties of the catalyst. The results shows that Ni/Ce (10:90)/Al2O3 catalyst successfully reduced TAN in crude oil to 0.50 from 4.22 mg KOH/g at 1000°C calcination temperature and catalyst loading of 0.39% (7 beads). XRD analysis proposed Al2O3 and CeO2 fcc was the active site for Ni/Ce (10:90)/Al2O3 catalyst. C-H alkanes stretching, -CH2- alkanes stretching and pure metal oxides stretching modes were detected on the catalyst at wavelength of 2952.49 to 2852.82, 1599.38, and 862.81 to 537.27 cm-1 respectively by FTIR analysis after catalytic deacidification process which indicates that there were impurities that have adsorbed on the catalyst surface. As a conclusion, the catalysts successfully reduced the TAN value of acidic crude oil to less than 1.00 mg KOH/g.

Experimental Analysis of Alkali-Brine-Alcohol Phase Behavior with High Acid Number Crude Oil

SummaryA potential enhanced oil recovery technique is to inject alkali into a reservoir with a high-total acid number (TAN) crude to generate soap in situ and reduce interfacial tension (IFT) without the need to inject surfactant. The method may be cost-effective if the IFT can be lowered enough to cause significant mobilization of trapped oil while also avoiding formation of gels and viscous phases.This paper investigates the potential field application of injecting alkali to generate in-situ soap and favorable phase behavior for a high-TAN oil. Oil analyses show that the acids in the crude are a complex mixture of various polar acids and not mainly carboxylic acids. The results from phase behavior experiments do not undergo typical Winsor microemulsion behavior transition and subsequent ultralow IFTs below 1×10−3 mN/m that are conventionally observed. Instead, mixing of alkali and crude/brine generate water-in-oil macroemulsions that can be highly viscous. For a specific range of alkali concentrations, however, phases are not too viscous, and IFTs are reduced by several orders of magnitude. Incremental coreflood recoveries in this alkali range are excellent, even though not all trapped oil is mobilized.The viscous phase behavior at high alkali concentrations is explained by the formation of salt-crude complexes, created by acids from the crude oil under the alkali environment. These hydrophobic molecules tend to agglomerate at the oil-water interface. Together with polar components from the crude oil, they can organize into a highly viscous network and stabilize water droplets in the oleic phase. Oil-soluble alcohol was added to counter those two phenomena at large concentrations, but typical Winsor phase behavior was still not observed. A physicochemical model is proposed to explain the salt-crude complex formation at the oil-water interface that inhibits classical Winsor behavior.

Stabilization of acid-rich bio-oil by catalytic mild hydrotreating.

Although liquid products derived from the pyrolysis of biomass are promising for the production of petroleum-like hydrocarbon fuels, the catalytic burden of hydrodeoxygenation must be reduced to achieve feasible upgrading processes. Herein, mild hydrotreating of an acid-rich biomass pyrolysis oil (bio-oil) with an unusually high total acid number (588mg KOH/g bio-oil) was performed to stabilize the low-quality bio-oil. Ru-added TiO2-supported transition metal catalysts stabilized the bio-oil by reducing its acidity more compared to what could be achieved by Ru-free catalysts; this process also leads to lower loss of organic compounds compared to when using a Ru/TiO2 catalyst. Based on the performance of transition metal catalysts, including Ni, Co, and Cu, supported on TiO2, tungstate-zirconia, or SiO2, supported bimetallic catalysts were prepared by adding Ru to the TiO2-supported metal catalysts. The bimetallic catalysts Ru/Ni/TiO2 and Ru/Co/TiO2 exhibited good decarboxylation activity for the removal of carboxylic acids and a higher yield of organic compounds compared to that provided by Ru, which can be deemed appropriate for feedstocks when hydrodeoxygenation needs to suppress the loss of organic reactants. Using these catalysts, the carboxylic acid concentration was reduced to 319-323mg KOH/g bio-oil with organic yields of 62-63wt% at reaction temperatures 150-170°C lower than the temperature required for direct conversion of carboxylic acids to alcohols or deoxygenates. The improved catalytic hydrotreating activity of Ru-added transition metals can be attributed to the high acid site densities of these catalysts along with their improved hydrogenation activities.