Low Total Acid Number Research Articles

Characterization and Combustion of Crude Thermal Deoxygenation Oils Derived From Hydrolyzed Woody Biomass

Thermal Deoxygenation (TDO) is a reaction converting calcium-neutralized, biomass-derived acids to crude hydrocarbons at 450 °C in an inert atmosphere at ambient pressure. In this work, TDO is applied to hydrolyzate produced by the Biofine process to determine the effects of impurities on TDO oil yield and composition. The oils were characterized for fuel and material properties according to ASTM methods. The oils were found to have low total acid number (<1.4) and a consistent boiling point distribution according to high temperature simulated distillation (ASTM 7169) of between 75° and 585 °C. Combustion and emission characteristics of TDO crude oil as a 50/50 vol. % blend with ultralow sulfur diesel were consistent with fuels of low cetane number. This is attributed to the low hydrogen content of the oils (9.4 wt %) and high aromaticity.

The removal of naphthenic acids from dewaxed VGO via esterification catalyzed by Mg–Al hydrotalcite

This work focused on deacidification of dewaxed VGO by esterification on solid base hydrotalcite catalyst to achieve the target of lowering the total acid number (TAN) of oil. Mg–Al hydrotalcite with Mg/Al molar ratio of 4 was synthesized via urea method, and followed by calcination and rehydratation. Mg–Al hydrotalcite and its calcined and rehydrated products were characterized by PXRD, BET, CO2-TPD, FTIR, and TG/DTA. The catalytic activity of the prepared catalyst was evaluated using batch reactor for investigating the conversion of naphthenic acids in dewaxed VGO. The effects of various reaction parameters such as mass ratio of glycol to oil, mass ratio of catalyst to oil, temperature, time etc. on the conversion of naphthenic acids were studied and the findings were discussed. The activity of the calcined catalyst was lower than the initial activity of the non-calcined catalytic system. The correlation between the basic properties of the solid catalysts and the activity in the esterification in dewaxed VGO was investigated. The basic Brønsted sites played an important role in the esterification process. The hydrotalcite catalyst rehydrated by water exhibited a slight higher esterification efficiency compared to the as-synthesized one, and the as-synthesized one can be reused several times without significant loss of activity. Therefore, it was verified that Mg–Al hydrotalcite as a heterogeneous catalyst could be used to esterify naphthenic acids to lower TAN value of oil effectively, and Mg–Al hydrotalcite may be a promising catalyst for its sufficient high catalytic activity and stability.

Study on the variation of dynamic interfacial tension in the process of alkaline flooding for heavy oil

Experimental investigations have been conducted to elucidate the variation of the dynamic interfacial tension (DIFT) in the process of alkaline flooding for heavy oil. The Binnan heavy oil with high TAN (Total Acid Number) and the Zhuangxi heavy oil with low TAN were pre-equilibrated by long-term contacting with NaOH and Na2CO3 solutions. The results show that the heavy oil pre-equilibrated by NaOH solutions almost loses the interfacial activity, and the IFT increases a lot. Although there is still interfacial activity in the heavy oil which is pre-equilibrated by Na2CO3 solutions, and the dynamic interfacial tension minimum (DIFTmin) changes a little, yet the dynamic interfacial tension equilibrium value (DIFTeq) increases a lot. The effect of interfacial reaction on the interfacial property of oil with low TAN is more severe than that with high TAN. When the alkaline concentration is larger than a certain value, the IFT between the fresh oil with high TAN and the equilibrated alkaline solutions can decrease to ultralow after interfacial reaction, and the Na2CO3 system is superior to the NaOH system. However, the IFT between the fresh oil with low TAN and the equilibrated alkaline solutions increases after interfacial reaction. The above results can be used as guidance in the formulation design and mechanisms studies of alkaline flooding for improved heavy oil recovery.

Production and Analysis of Fast Pyrolysis Oils from Proteinaceous Biomass

Fast pyrolysis of lignocellulosic biomass is a facile method for producing high yields of liquid fuel intermediates. However, because most fast pyrolysis oils are highly oxygenated, acidic, and unstable, identification of feedstocks that produce higher quality pyrolysis liquids is desirable. Therefore, the effect of feedstock protein content was studied by performing fast pyrolysis experiments on biomass with varying protein content. The feedstocks ranged from low-protein content, ∼5% up to feedstocks with >40 wt.% protein content. Protein content was not a major factor in the yield of pyrolysis oil or the distribution of biomass carbon into the pyrolysis products. However, elevated levels of protein did cause a deoxygenation effect in the pyrolysis process with more of the oxygen rejected from the biomass as water. The deoxygenation caused the pyrolysis oil from the higher protein containing biomass to have higher energy content. Furthermore, the concentration of basic nitrogen groups caused the pyrolysis oil from the higher protein biomass to shift to a more neutral pH and lower total acid number than has been measured typically for lignocelluloic biomass pyrolysis oils. Some of the pyrolysis oils, particularly those from the mustard seed family presscakes exhibited better thermal stability than low-protein pyrolysis oils.

Role of Naphthenic Acids in Emulsion Tightness for a Low Total Acid Number (TAN)/High Asphaltenes Oil: Characterization of the Interfacial Chemistry

The detailed composition of a low total acid number (TAN) crude oil that causes unusually severe water−oil emulsion problems along the production stream was studied by Fourier transform ion cyclotron resonance mass spectrometry and infrared spectroscopy. Distinct fractions, such as asphaltenes, whole interfacial material, extracts from the interfacial material, etc., were prepared for characterization. The detailed compositional analysis of the interfacial material showed the predominance of asphaltenes together with high amounts of distinctive mono- and diprotic naphthenic acids and sulfur- and oxygen-containing aromatic molecules. In addition, the interface was found to be heterogeneous. A primary group of species that is strongly bonded to the water surface consists of fatty monoprotic acids, fatty, naphthenic, and aromatic diprotic acids, and some alkyl benzene sulfonates. A secondary part of interfacial material consists of various classical asphaltene-related components, such as aromatic sulfur−oxyg...

Naphthenic acid removal from crude oil through catalytic decarboxylation on magnesium oxide

Naphthenic acid (NA) has been recognized as one of the major sources of corrosion in oil production and refining. In this study, catalytic decarboxylation of carboxylic acid model compounds and naphthenic acid removal from crude oil were investigated. A metal oxide catalyst, MgO has been developed and its effectiveness in catalyzing decarboxylation reactions involving carboxylic acid compounds such as naphthoic acid has been determined based on the formation of CO 2 and the conversion of acid. The major reaction takes place in the temperature range of 150–300 °C. The role of MgO in the system is considered to be multiple. It has the ability to adsorb acidic compounds via acid–base neutralization and it can also promote reactions such as decarboxylation and hydrocarbon cracking at the increased temperature. Direct application of MgO to crude oil results in significant naphthenic acid removal and lower total acidity of the oil as evidenced by a decrease in RC OOH concentration as determined by FT-IR and a lower total acid number (TAN).

Study on high-temperature naphthenic acid corrosion and erosion-corrosion of aluminized carbon steel

High-temperature naphthenic acid corrosion (NAC) and erosion-corrosion (NAEC) behaviors of pack-aluminized carbon steel have been investigated in laboratory to evaluate the resistance of aluminized layer to the NAC and NAEC. A field erosion-corrosion test of 700 days was also performed in an oil refinery. Parallel tests were carried out for carbon steel. It was found that the aluminized steel exhibited a better NAC resistance only at early testing stage than the carbon steel in high total-acid-number (TAN) environment. The NAC resistance degraded rapidly with increasing testing time, and became even worse than that of the carbon steel at final testing stage, accompanying a step-like or lamellar spallation in the aluminized layer. In low TAN environment, the aluminized steel exhibited a much better resistance to both the NAC and NAEC in comparison with the carbon steel. Similarly a good erosion-corrosion resistance was found for the aluminized steel in actual oil-refining environment although relatively serious erosion-corrosion attack simultaneously took place in the aluminized layer. Based on the above results, possible NAC and NAEC mechanisms for the aluminized steel are discussed.