Lube Base Oil Research Articles

An optimization based strategy for crude selection in a refinery with lube hydro-processing

An optimization-based strategy is developed for crude selection in a refinery with lube base oil (LBO) producing capability. Crude oil is classified into five types based on the viscosity index (VI) and the compositional aspect of vacuum gas oil (VGO). A prediction model for the VI, the most important quality variable in LBO processing, is developed for VGO based on its bulk properties. For each crude type, prediction models for the yield and the VI change vs. the conversion rate during lube hydro-processing are developed. The lube hydro-processing models are then incorporated into the overall refinery optimization to maximize the overall margin while satisfying all the specifications of the lube and fuel products simultaneously. A case study involving several price scenarios illustrates the benefits from using the model-based optimization method for deciding crude procurement, the grade of the LBO to be produced, and the conversion rate in the lube process.

Change of Hydrocarbon Structure Type in Lube Hydroprocessing and Correlation Model for Viscosity Index

Viscosity index (VI) is one of the most important properties that determine the quality grade of lube base oil and it strongly depends on the molecular structure of the hydrocarbon constitute. To produce group III base oil, which is the most valuable base oil type, through lube hydroprocessing, the VI of the final product should be over 120. However, rigorous studies and analyses on the compositional change in lube hydroprocessing and a practical correlation model for VI with respect to the chemical compositions are still lacking. In this study, pilot tests for lube hydroprocessing, which is composed of hydrotreating/cracking followed by hydroisomerization, are implemented with three different types of feedstocks (paraffinic, intermediate, and naphthenic vacuum gas oils) and under different reaction conditions (catalyst and temperature). The fractional changes of the hydrocarbon components by the lube hydroprocessing reactions are quantitatively confirmed using a gas chromatography with mass selective det...

Octadecanethiol-grafted molybdenum disulfide nanosheets as oil-dispersible additive for reduction of friction and wear

Molybdenum disulfide (MoS2) easily shears at the contact interfaces because of weak interplaner interaction and exhibits high mechanical strength, which promises its potential for tribological applications. However, poor dispersibility of MoS2 in the lube oils has been a great challenge. Herein, a facile and scalable hydrothermal approach is presented to synthesize the MoS2 nanosheets and then chemically functionalized with octadecanethiol (ODT). The structural defects and vacant sulfur sites on the Mo-atoms of MoS2 nanosheets are targeted for grafting of ODT via Mo-S dative linkage. The chemical and structural features of MoS2-ODT are characterized by FTIR, XPS, XRD and HRTEM analyses. The dispersion stability of MoS2-ODT nanosheets in the polyol ester lube oil is examined by UV–Visible spectroscopy. The van der Waals interaction between the octadecyl chain of MoS2-ODT and oleate chains of polyol ester lube oil facilitates the dispersion of MoS2-ODT nanosheets. Tribological results revealed that minute dosing (0.05mg.mL−1) of thoroughly dispersed MoS2-ODT nanosheets, as an additive to polyol lube oil, significantly reduced the friction and the wear of steel tribo-pair. The uninterrupted supply of MoS2-ODT nanosheets on the tribo-contacts, formation of MoS2 thin film on tribo-interfaces, ease of shearing driven by weak van der Waals interaction between MoS2 lamellae and high mechanical strength of MoS2, collectively enhanced the tribo-performance, when thoroughly dispersed MoS2-ODT was used as an additive to the polyol lube base oil.

Novel Triazine Schiff Base-Based Cationic Gemini Surfactants: Synthesis and Their Evaluation as Antiwear, Antifriction, and Anticorrosive Additives in Polyol

Two novel triazine Schiff base-based cationic gemini surfactants namely N,N′-bis{(p-(N,N,N-tetradecyldimethylammonium bromide)benzylidene} 6-methyl-1,3,5-triazine-2,4-diamine (14-MTR-14) and N,N′-bis{(p-(N,N,N-tetradecyldimethylammonium bromide)benzylidene} 6-phenyl-1,3,5-triazine-2,4-diamine (14-PTR-14) were synthesized following the two-step reaction. First the intermediate adduct was synthesized by reaction of the 4-(dimethylamino)benzaldehyde with 1-bromotetradecane. In the second step, the germinal surfactants 14-MTR-14 and 14-PTR-14 were synthesized by imine coupling with this intermediate adduct with 6-methyl-1,3,5-triazine-2,4-diamine and 6-phenyl-1,3,5-triazine-2,4-diamine, respectively. Both were characterized using elemental analysis (CHN), infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetry (TG). The compounds were then evaluated as anticorrosive and lubricity improver additive in polyol lube base oil. Both the surfactants show the similar anticorros...

Fatty-Acid-Constituted Halogen-Free Ionic Liquids as Renewable, Environmentally Friendly, and High-Performance Lubricant Additives

Stearic, oleic, and linoleic acids, which have a variable degree of unsaturation (n = 0, 1, and 2, respectively), were selected as model fatty acids to synthesize halogen-free, renewable, and environmentally friendly ionic liquids. The preparation of fatty acid ionic liquids was confirmed by 1H and 13C NMR and FTIR analyses. The fatty acid ionic liquids as additives to the polyol ester lube base oil exhibited remarkably improved friction and antiwear properties for steel tribopair. The fatty acid anions exhibiting inherent negative charge promptly interact with the engineering surfaces compared with the polyol ester and vegetable oils. Therefore, the addition of 2% fatty acid ionic liquid to the polyol ester, which is composed of fatty acid, showed remarkable improvement in both the friction-reducing (28–60%) and the antiwear (20–28%) properties under the boundary lubrication regime. The magnitudes of friction and wear reduction are largely controlled by the degree of unsaturation in the fatty acid anion....

Alkylamine-functionalized hexagonal boron nitride nanoplatelets as a novel material for the reduction of friction and wear.

Hexagonal boron nitride nanoplatelets (h-BNNPs), which are structurally analogous to graphene, were prepared via the ultrasound-assisted exfoliation of h-BN powder using N-methyl pyrrolidone as the solvent. The alkylamines with variable alkyl chains and electron-rich nitrogen atoms were grafted onto the boron sites of the h-BNNPs based on Lewis acid-base chemistry. The grafting of the alkylamines onto the h-BNNPs was confirmed using FTIR, XPS, TGA and (13)C SSNMR analyses. The crystalline and structural features of the alkylamine-functionalized h-BNNPs were studied using XRD and HRTEM analyses. The TGA and FTIR results revealed a higher grafting of octadecylamine (ODA) on the h-BNNPs compared to trioctylamine (TOA). The cohesive interaction between the alkyl chains grafted onto the h-BNNPs and the hydrocarbon chains of mineral lube base oil facilitates the dispersion of the alkylamine-functionalized h-BNNPs. The TOA-grafted h-BNNPs (h-BNNPs-TOA) exhibited long-term dispersion stability compared to the ODA-grafted h-BNNPs and this was attributed to a higher degree of van der Waals interactions between the octyl chains of the TOA molecules grafted onto the h-BNNPs and the hydrocarbon chains of the mineral lube base oil. The tribo-performance of the h-BNNPs-TOA as an additive to mineral lube base oil was evaluated in terms of the coefficient of friction and wear using ball-on-disc contact geometry. A minute dosing (0.02 mg mL(-1)) of h-BNNPs-TOA significantly improved the lubrication characteristics of the mineral lube base oil and showed a 35 and 25% reduction of friction and wear, respectively. The presence of boron and nitrogen on the worn scar of an aluminium disc, as deduced from elemental mapping, confirmed the formation of a tribo-chemical thin film of h-BN lamellae on the contact interfaces, which not only reduced the friction but also protected the contact interfaces against undesirable wear events.

Antimicrobial and lubrication properties of 1-acetyl-3-hexylbenzotriazolium benzoate/sorbate ionic liquids

1-Acetyl-3-hexylbenzotriazolium cation-based ionic liquids exhibit antimicrobial activities and improve the lubrication properties of lube base oil by reduction of friction and wear.

Fatty acid ionic liquids as environmentally friendly lubricants for low friction and wear

Tetrabutylammonium-fatty acids ionic liquids as lubricants exhibited significantly lower friction compared to polyol ester lube base oil.

Hydrocracking of Polyolefin Thermal Cracking Waxes Over Ni-loaded Molecular Sieve Catalysts

The hydrocracking of thermal cracking waxes obtained from pyrolysis of polyolefin at 360°C for 120 min has been studied using Ni-loaded molecular sieves catalysts. According to XRD, TPR, and BET data, the presence of nickel oxide did not seem to damage the crystalline framework of the catalytic supports. Hydrocracking experiments were carried out in a stirred autoclave reactor at 300°C for 120 min under 2.0 MPa of hydrogen. The results suggested the existence of a balance between the acid and metal function over bifunctional catalysts, which affects hydrogenation and hydroisomerization of thermal cracking waxes. Hydrocracking reactions took place extensively over mixture of Ni/HBeta and ZSM-5, leading toward higher fractions of gases (30.2%) and diesel (23.5%). The higher fractions of gasoline (33.5%) and lube base oil (19.0%) were obtained over mixture of Ni/HSAPO-11 and ZSM-5. In contrast, hydrocracking reaction occurred in a lower extent over mixture of Ni/NMCM-41 and ZSM-5, which produces lube base oil with lower pour point (–10°C), gasoline and diesel with lower bromine numbers (1.1 and 0.8 g Br2/100 g sample). The viscosity index of lube base oil was in the range of 131–171 over all three mixed catalysts.

Alkyl-chain-grafted hexagonal boron nitride nanoplatelets as oil-dispersible additives for friction and wear reduction.

Hexagonal boron nitride (h-BN), an isoelectric analogous to graphene multilayer, can easily shear at the contact interfaces and exhibits excellent mechanical strength, higher thermal stability, and resistance toward oxidation, which makes it a promising material for potential lubricant applications. However, the poor dispersibility of h-BN in lube base oil has been a major obstacle. Herein, h-BN powder was exfoliated into h-BN nanoplatelets (h-BNNPs), and then long alkyl chains were chemically grafted, targeting the basal plane defect and edge sites of h-BNNPs. The chemical and structural features of octadecyltriethoxysilane-functionalized h-BNNPs (h-BNNPs-ODTES) were studied by FTIR, XPS, XRD, HRTEM, and TGA analyses. The h-BNNPs-ODTES exhibit long-term dispersion stability in synthetic polyol ester lube base oil because of van der Waals interaction between the octadecyl chains of h-BNNPs-ODTES and alkyl functionalities of polyol ester. Micro- and macrotribology results showed that h-BNNPs-ODTES, as an additive to synthetic polyol ester, significantly reduced both the friction and wear of steel disks. Elemental mapping of the worn area explicitly demonstrates the transfer of h-BNNPs-ODTES on the contact interfaces. Furthermore, insight into the lubrication mechanism for reduction in both friction and wear is deduced based on the experimental results.

Solutions of Lube Base Oil Not Meeting Acid Value Requirement

Two solutions of producing HVI400SN lube base oil meeting acid number requirement were determined. One solution was that optimum operation conditions were found by optimization solution of single-stage extraction experiment data (i.e., the solvent/oil ratio was 5, the top and bottom temperatures of extractor were 120°C and 80°C, respectively). Another solution was that at least four theoretical plates were required after transformation of the existing furfural extractor, and verification results of pilot test showed viscosity index of refined oil was 106 and acid number was 0.0174 mg (KOH)/g under current operation conditions of industrial extractor.

Investigation on the Potential of Dextrose, Sucrose and Cellulose Dodecenylsuccinate Esters as Lubricity Additive

As a consequence of the environmental issues and the increasing global demand of the lubricants, we need to have the sustainable raw material sources not only for the lube base oil but also for additives. In view of this, we have synthesized the dodecenylsuccinate (DDSA) ester of dextrose (sample 1), sucrose (sample 2) and cellulose (sample 6) with almost same degree of substitution (DS ~2.0). The lubricity was observed for these synthesized samples in n-decane which was taken as lubricant reference base fluid. The lubricity tests were carried out as per the ASTM D6079 using high frequency reciprocating test rig. It was observed that the dextrose-DDSA ester shows good lubricity properties in comparison to sucrose and cellulose. 1 % sucrose-DDSA in n-decane has decreased the value of wear scar diameter from 800 to 515 µm while the values for sucrose-DDSA and cellulose-DDSA were found to be 565 and 590 µm respectively. Further, to see the effect of varying DS over the lubricity in the case of cellulose-DDSA esters, the four cellulose ester samples (sample 3–6) with varying DS (0.68, 0.95, 1.43 and 2.03) were prepared and evaluated. It was also observed that the lubricity increases with the increasing DS value in cellulose-DDSA esters.

Physical and rheological properties of deasphalted oil produced from solvent deasphalting

Abstract Because of the depletion of conventional oil and its increasing price, technologies that use unconventional oil and low-value crude residues are attracting great attention. Unconventional oil and low-value crude residues contain large amounts of asphaltene, which leads to high viscosity and includes a considerable amount of nitrogen, sulfur, and various metals. Therefore, to utilize such energy resources, asphaltene-removal processes (e.g., solvent deasphalting) are required to obtain deasphalted oil (DAO). DAO is generally used for lube base oils and is converted into transportation fuel and petrochemical raw materials by additional refinement. Herein, the physical and rheological properties of DAO were investigated to develop a better understanding of the DAO characteristics and its efficient utilization. The physical properties of DAO were analyzed by measuring elemental compositions; American Petroleum Institute gravity; saturates, aromatics, resins, and asphaltenes fractions; and boiling-point distributions, and the properties were compared with those of vacuum residues. The DAO viscosity was characterized using a rotational rheometer at various temperatures to analyze the effect of temperature on the DAO fluidity. The DAO viscosity greatly decreased with increasing temperatures and a distinctive transition was observed at ∼70 °C. In the shear viscosity and modulus analyses, DAO exhibited non-Newtonian behavior below 70 °C and Newtonian behavior above 70 °C.

Study of Novel Ecofriendly Multifunctional Lube Additives Based on Pentaerythritol Phenolic Ester

The concept of an “ecofriendly lubricant” has drawn much attention due to environmental issues related to conventional lubricants. Mere innovations in lube base oils are not enough. The introduction of new ecofriendly additives is also necessary to address such issues. Therefore, there is a need for the development of new multifunctional additives (MFA) that are environmentally benign. In view of this, the mixed esters of pentaerythritol monooleate with gallic acid (additive 1) and 3,5-di-tert-butyl-4-hydroxybenzoic acid (additive 2) have been synthesized. Both additives 1 and 2 were characterized by FT-IR, NMR, TG, and CHNS analyses. They were evaluated for antioxidant and detergent dispersant along with lubricity properties using the rotary bomb oxidation test, blotter spot test, and four ball test. The thermo-oxidative stability of the base oil was found to increase significantly in the presence of additives 1 and 2 at 3000 ppm concentration. The antioxidant, detergent dispersant, and lubricity propert...

A Study of the Regenerating Effects of Recycling Agents on Aged Asphalts

A new recycling agent for restoring aged asphalt was synthesized by using furfural extract oil and lube base oil as base oils and an additive as low temperature performance enhancer. The regenerating effects of different recycling agents were investigated. Then, the antiaging properties of recycled asphalts and the compatibility between recycling agents and aged asphalts were studied. Experimental results showed that the new recycling agent synthesized in this study had better regenerating effects than the other two recycling agents and different recycling agents and different aged asphalts had disparate compatibility.

Performance of Zinc-Difattyalkyldithyocarbamate as Anti-Friction/Anti-Wear Lubricant Additives

Dithyocarbamate is an organosulphur compound that has long been known and widely applied in various fields, including in agriculture and industry. Several variants of synthesized vegetable oil-based Zinc-difattyalkyldithyocarbamate were tested its anti-friction/anti-wear performance on four ball machine using the method of ASTM-D2783. Anti-friction/anti-wear test to six of additive variants of Zinc-difattyalkyldithyocarbamate at doses of 1.2% indicated that all variants of the product has welding point value higher than the lube base oil lubricant HVI 60, and from US Steel 136 standard for Hydraulic lubricants, but only two additive variants of Zinc-bis(lauryl palmityl)dithyocarbamate and Zinc-bis(lauryl oleyl)dithyocarbamate which has a larger load wear index value than the standard, and meet the criteria as an additive extreme pressure according to US steel 136 standard. Zinc-bis(lauryl palmityl)dithyocarbamate is an additive variant with the best performance, meet bi-functional lubricant additives criteria, as anti-friction/anti-wear and antioxidant additive.

Characterization of Basic Nitrogen-Containing Compounds in the Products of Lube Base Oil Processing by Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

The distribution of basic nitrogen-containing compounds in three vacuum gas oils (VGOs) with different boiling ranges and their dewaxed oils from the lube base oil refining unit of a refinery were characterized by positive-ion electrospray ionization (ESI) Fourier transform-ion cyclotron resonance mass spectrometry (FTICR MS). It turned out that the composition of basic nitrogen compounds in the samples varied significantly in DBE and carbon number, and the dominant basic N-containing compounds in these oil samples were N1 class species. N1O1, N1O2, and N2 class species with much lower relative abundance were also identified. The composition of basic nitrogen compounds in VGOs and dewaxed VGOs were correlated with increased boiling point and varied in DBE and carbon numbers. The comparison of the analytical results between VGOs and dewaxed VGOs indicated that more basic N-containing compounds in VGO with low carbon number and small molecular weight tend to be removed by solvent refining in lube base oil processing.

Optimizing the Process Conditions for the Production of Lube Base Oil From Heavy Distillate

In order to meet the increasing process demand of heavy crude, the deep processing of heavy oils, especially the vacuum residue, may be a best choice. The authors selected ketone-benzol dewaxing, furfural refining, clay finishing (AFC); and furfural refining, ketone-benzol dewaxing, clay finishing (FAC) were selected to process base oils. Elemental analysis, n-d-M method, and 1H nuclear magnetic resonance were used to investigate the structure characteristics of base oils. Experimental data show that the FAC process conditions are more rigorous than AFC process, the yield of AFC process is higher than that of FAC process, but their base oils have their advantages and disadvantages.

Enhancement of the spectral selectivity of complex samples by measuring them in a frozen state at low temperatures in order to improve accuracy for quantitative analysis. Part II. Determination of viscosity for lube base oils using Raman spectroscopy

The use of selectivity-enhanced Raman spectra of lube base oil (LBO) samples achieved by the spectral collection under frozen conditions at low temperatures was effective for improving accuracy for the determination of the kinematic viscosity at 40 °C (KV@40). A collection of Raman spectra from samples cooled around -160 °C provided the most accurate measurement of KV@40. Components of the LBO samples were mainly long-chain hydrocarbons with molecular structures that were deformable when these were frozen, and the different structural deformabilities of the components enhanced spectral selectivity among the samples. To study the structural variation of components according to the change of sample temperature from cryogenic to ambient condition, n-heptadecane and pristane (2,6,10,14-tetramethylpentadecane) were selected as representative components of LBO samples, and their temperature-induced spectral features as well as the corresponding spectral loadings were investigated. A two-dimensional (2D) correlation analysis was also employed to explain the origin for the improved accuracy. The asynchronous 2D correlation pattern was simplest at the optimal temperature, indicating the occurrence of distinct and selective spectral variations, which enabled the variation of KV@40 of LBO samples to be more accurately assessed.

Use of temperature dependent Raman spectra to improve accuracy for analysis of complex oil-based samples: Lube base oils and adulterated olive oils

A simple and effective strategy to improve accuracy for Raman spectroscopic analysis of complex mixture samples by probing a measurement temperature yielding enhanced spectral selectivity has been demonstrated. For the evaluation, the determination of Kinematic Viscosity at 40°C (KV@40) of lube base oil (LBO) samples was initially attempted. Partial least squares (PLS) was used to determine the KV@40 using Raman spectra of the samples collected at 8 different temperatures from 20 to 90°C with 10°C increments. Interestingly, the distinct temperature-induced spectral variation among the samples occurred at 50°C, thereby resulting in the improved accuracy for determination of KV@40. Two-dimensional (2D) correlation analysis was also performed to find an additional supportive rationale for the improved accuracy. The strategy was further evaluated for the identification of soybean oil-adulterated olive oils using linear discriminant analysis (LDA). Similarly, the discrimination accuracy was improved around 80–90°C due to the enhanced spectral selectivity between olive and soybean oils. In overall, these two results successfully demonstrate analytical effectiveness of the strategy.