Influence of Impurities and Oxidation on Hydroconversion of Waste Cooking Oil into Bio-jet Fuel

The influences of impurities and oxidation evolution of waste cooking oil on the preparation of bio-jet fuel via hydroconversion were studied. The hydrogenation active sites and acid sites were covered by heavy metals, sulfides, and basic nitrogen compounds, resulting in the increase of selectivity for bio-jet fuel by decreasing the selectivity of diesel, aromatics, and iso-alkanes. The effects of impurities, oxidation on the reaction pathway, and product distribution became more distinct with higher catalyst acidity. The evolution and variation of naphthalene, indan, and phenanthrene obtained from cyclic fatty acids influenced the properties of fuel or evoked the catalyst deactivation. This work will help to design new catalysts for selective conversion of waste cooking oil into bio-jet fuel.     

Co‐processing of Waste Cooking Oil and Light Cycle Oil with NiW/(Pseudoboehmite + SBA‐15) Catalyst

Light cycle oil (LCO) and waste sunflower cooking oil (WSO) were co‐processed with the aim of obtaining more environmentally friendly fuels. Partial hydrogenation of naphthalene was also investigated as a model reaction. Commercial NiW/SiO₂‐Al₂O₃, as a reference catalyst, and NiW/(pseudoboehmite + SBA‐15), as a new research catalyst, were tested. Liquid products were analyzed by simulated distillation, elemental analysis, and FTIR spectroscopy. Elemental analysis indicated higher efficiency of the research catalyst in hydrodesulfurization, hydrodenitrogenation, and hydrodeoxygenation of pure LCO and mixed feedstock containing WSO. Reactions with pure WSO resulted in less sulfur leaching into the product and a lower degree of deoxygenation compared with the commercial catalyst.     

Base‐Catalyzed Ethanolysis of Waste Cooking Oil in a Micro/Millireactor System: Flow and Reaction Analysis

An important way for the production of biodiesel is the base‐catalyzed transesterification of oil or fat with monohydric alcohols. Flow and reaction analysis with respect to the applicability of a micro/millireactor setup to two‐phase ethanolysis of waste cooking oil is described. The flow in the micro/millireactor system was examined on the example of a soybean oil/ethanol mixture and compared with a T‐mixer. Parallel and slug flow were observed in different reactor sections of the micro/milli‐reactor system and evaluated concerning their efficiency. A method for determination of the viscosity of the mixture was conducted and validated. Certain pretreatments were investigated with regard to the suitability of the waste cooking oil for ethanolysis. Relations between biodiesel yields and some oil properties like chain length and acid number were found.     

Effect of Different Cosolvents on Transesterification of Waste Cooking Oil in a Microreactor

Biodiesel was prepared from waste cooking oil combined with methanol. The process was performed via transesterification in a microreactor using kettle limescale as a heterogeneous catalyst and various cosolvents under different conditions. n‐Hexane and tetrahydrofuran were selected as cosolvents to investigate fatty acid methyl esters (FAMEs). To optimize the reaction conditions, the main parameters affecting FAME% including reaction temperature, catalyst concentration, oil‐to‐methanol volumetric ratio, and cosolvent‐to‐methanol volumetric ratio were studied via response surface methodology. Under optimal reaction conditions and in the presence of the cosolvents n‐hexane and tetrahydrofuran, high FAME purities were achieved. Considering the experimental results, the limescale catalyst is a unique material, and the cosolvent method can reduce significantly the reaction time and biodiesel production cost.     

Conjugated linoleic acid formation by hydrogenation/isomerisation of safflower oil over bifunctional structured catalyst Rh/SBA‐15

Directed isomerisation of safflower oil under very low hydrogen partial pressure of 7 psi over a novel bifunctional highly structured rhodium‐based catalyst (Rh/SBA‐15), having narrow pore size distribution ranging from 4 to 8 nm, and BET‐specific surface of ≈1,000 m² g^?1, was investigated as a new chemocatalytic approach for vegetable oil hardening and simultaneously producing health‐beneficial conjugated linoleic acids (CLA). Time course profiles of (cis‐9, trans‐11)‐; (cis‐10, trans‐12)‐; (trans‐10, cis‐12)‐; (cis,cis)‐ and (trans, trans)‐octadecadienoic isomers (CLAs) as well as the other fatty acids traditionally encountered during the hydrogenation of vegetable oils are presented and discussed under selected process conditions. Preliminary results show that it is possible to tailor characteristics of the hydrogenation catalyst in such way to confer its bi‐functional activity: hydrogenation and conjugation isomerisation. © 2011 Canadian Society for Chemical Engineering     

Effect of a Ni‐Based Catalyst on Bio‐Oil Upgrading under CO Atmosphere

A novel method of bio‐oil upgrading over Ni‐based catalysts under CO atmosphere and optimum conditions for a Ni/Cu/Zn/Al catalyst were determined. The oxygen content as well as the water content decreased significantly and the pH value of upgraded bio‐oil was higher than that of crude bio‐oil. The physical properties indicate that upgraded bio‐oil was more stable than crude bio‐oil.     

Optimization of a Mixed Additive and its Effect on Physicochemical Properties of Bio‐Oil

A final optimal mixed additive consisting of methanol, acetone, and ethyl acetate in specific proportions was obtained by one‐factor multi‐objective optimization of the Design‐Expert software and performed well in a verification experiment. The mixed additive of methanol and ethyl acetate was first prepared separately and then added to bio‐oil, followed by acetone. The viscosity of the additive/bio‐oil mixture was significantly lower than of the crude bio‐oil. Among all chemical compound groups in the bio‐oil, the content of phenols was the highest one. Chemical compounds in bio‐oil after aging had higher molecular mass weights than before. The addition of the final optimal mixed additive and the accelerated aging process could slightly change the intensity and positions of some absorption peaks.     

Bio‐Based Rubbers by Concurrent Cationic and Ring‐Opening Metathesis Polymerization of a Modified Linseed Oil

Bio‐based rubbers prepared by tandem cationic polymerization and ROMP using a norbornenyl‐modified linseed oil, Dilulin?, and a norbornene diester, NBDC, have been prepared and characterized. Increasing the concentration of the NBDC in the mixture results in a decrease in the glass transition temperature. The new bio‐based rubbers exhibit tensile test behavior ranging from relatively brittle (18% elongation) to moderately flexible (52% elongation) and with decreasing values of tensile stress with increasing NBDC content. Thermogravimetric analysis reveals that the bio‐based rubbers have maximum decomposition temperatures of over 450 °C with their thermal stability decreasing with increasing loadings of NBDC.

     

Kinetics of Bitumen‐Derived Gas Oil Upgrading Using a Commercial NiMo/Al2O3 Catalyst

Hydrotreating (HT) kinetics of Athabasca bitumen‐derived gas oil has been studied between 340 to 420°C using a commercial NiMo/γ‐Al₂O₃ catalyst. The kinetics analyses included overall conversion of high‐boiling species into low‐boiling products, hydrodenitrogenation (HDN) of total, basic and non‐basic nitrogen compounds and hydrodesulfurization (HDS). Three temperature regimes were marked out for the kinetic analyses: low (340‐370°C), intermediate (370‐400°C) and high (400‐420°C). The mechanism for the conversion of high to low‐boiling species was observed to change from one temperature regime to the other, giving rise to different activation energies. HDS and HDN activation energies increased in the order: high < low < intermediate severity temperature regime.     

Catalytic Hydrocracking of a Bitumen‐Derived Asphaltene over NiMo/γ‐Al2O3 at Various Temperatures

Hydrocracking of a bitumen‐derived asphaltene over NiMo/γ‐Al₂O₃ was investigated in a microbatch reactor at varying temperatures. The molar kinetics of asphaltene cracking reaction was examined by fitting the experimental data. Below a defined temperature, the molar reaction showed the first‐order kinetic feature while at higher temperatures secondary reactions such as coke formation became significant, causing deviation of the reaction behavior from the proposed first‐order kinetic model. Selectivity analysis proved that dominant products varied from gases to liquids to gases with increasing temperature, shifting the dominant reaction from C–S bonds cleavage to C–C bonds cleavage.     

Reaction Kinetics of Steam Reforming of n‐Butanol over a Ni/Hydrotalcite Catalyst

Pyrolytic lignin can be transformed to liquid transportation fuels by hydrotreatment, which requires hydrogen (H₂). Bio‐oil is a suitable renewable feedstock for H₂ production. Here, n‐butanol was chosen as a model compound representing alcohols in the bio‐oil aqueous fraction. H₂ production from steam reforming of n‐butanol was investigated in a fixed‐bed reactor using a commercial Ni/hydrotalcite catalyst. A plausible reaction pathway in the presence of Ni was discussed. An increase in reforming temperature, space time, and steam/carbon ratio in the feed enhanced the n‐butanol conversion and H₂ yield. Reaction kinetics was studied in the defined chemical control regime. The reaction order with respect to n‐butanol (one) and the activation energy were determined.