Biodiesel production by esterification of ricinoleic acid over a series of synthesized sulfated zirconia catalysts

A series of sulfated zirconia (SZ) were synthesized and evaluated for catalytic esterification of ricinoleic acid obtained from the castor oil with butanol at 110 °C. The effect of alcohols’ chain length was studied using butanol (C4), propanol (C3), ethanol (C2) and methanol (C1) at 65 °C, and reflux of corresponding alcohol boiling points. The synthesized catalysts were characterized using nitrogen porosimetry, X-ray powder diffraction, thermogravimetric analysis and Diffuse Reflectance Infrared Fourier Transform Spectroscopy. Analysis of ricinoleic conversion was performed using gas chromatography. Sulfuric acid loading improved the surface area of zirconia at a lower dose. The surface areas of the catalysts increased as the concentrations of sulfuric acid solution were increased from 0.025 to 0.10 M, after which the decline was observed. SZ obtained at 0.05 M H2SO4 (0.05SZ) gave the optimal catalytic activity compared to the other series of SZ used. The ricinoleic acid conversion decreased with increase of alcohol alkyl chain from C1-C4 at 65 °C, but increased under the reflux temperature of the corresponding alcohols, with the maximum conversion being 47% at 118 °C for the reaction involving butanol. Overall, the synthesized SZ catalysts are deployable in biodiesel production from castor oil upon optimizing other conditions. Keywords: Ricinoleic acid; Sulfated zirconia; Biodiesel production

The use of fluorinated alumina as a support of the sulfated zirconia catalyst for isomerization of hexane

The study considers the effect of fluorine doping of the alumina matrix used for the synthesis of supported sulfated zirconia catalysts. Hydrofluoric acid served as a fluorinating agent. The addition of fluorine was shown to affect the textural characteristics of the Al2O3 matrix and hence the surface area of sulfated zirconia catalysts based on the doped systems. It was found that the introduction of fluorine into the catalysts increases their activity (the conversion of hexane) and the yield of high-octane isomer 2,2-dimethylbutane.

The promotion of supported sulfated zirconia catalysts by iron and manganese sulfates

The study considers the effect of iron and manganese introduction on the textural characteristics and phase composition of the alumina matrix used as a support for sulfated zirconia catalysts in hexane isomerization. The additives introduced during plasticization of aluminum hydroxide essentially enhance the catalytic activity, which is expressed in terms of hexane conversion, and the selectivity of isomerization toward the formation of hexane isomers. The distinctive feature of the doped catalysts is the formation of acid sites with LAS/BAS ≥ 2, which promote an increase in the yield of isomers and particularly the yield of high-octane 2,2-dimethylbutane.

Butane Isomerization as a Diagnostic Tool in the Rational Design of Solid Acid Catalysts

The growing demand for isobutane as a vital petrochemical feedstock and chemical intermediate has for many decades surpassed industrial outputs that can be supplied through liquified petroleum gases. Alternative methods to resource the isobutane market have been explored, primarily the isomerization of linear n-butane to the substituted isobutane. To date the isobutane market is valued at over 20 billion US dollars, enticing researchers to seek unique and novel catalytic materials to improve on current commercial practices. Two main classes of catalysts have dominated the butane isomerization literature in the last few decades; namely microporous zeolites and sulfated zirconia. Both have been widely researched for butane isomerization, to the point where key catalytic descriptors such as acidity, framework topology and metal doping are becoming well understood. While this provides new researchers with a roadmap for developing new materials, it is has also begun developing into an invaluable tool for diagnosing and understanding the effect of these individual descriptors on catalytic properties. In this review we explore the different factors that influence the active site behavior of particularly zeolites and sulfated zirconia catalysts towards understanding the use of butane isomerization as a diagnostic tool for solid-acid catalysts.