Comparison of Synthetic and Natural Zeolite Catalysts’ Behavior in the Production of Lactic Acid and Ethyl Lactate from Biomass-Derived Dihydroxyacetone

This article presents the results of the conversion of dihydroxyacetone (DHA) to lactic acid (LA) with the use of zeolite catalysts. For this purpose, synthetic zeolite beta (BEA) and natural clinoptilolite (CLI) were used as a matrix. The zeolites were modified with various metals (Sn, Fe, Cu and Zn) during ion exchange under hydrothermal conditions. The DHA conversion process with the participation of metal-functionalized zeolites allowed us to obtain intermediates, i.e., pyruvic aldehyde (PAL), which during the further reaction was transformed into a mixture of products such as ethyl lactate (EL), pyruvic aldehyde (PA), lactic acid and ethyl acetate (EA). The best selectivity towards lactic acid was achieved using Sn-CLI (100%) > Na-BEA (98.7%) > Sn-BEA (95.9%) > Cu-BEA (92.9%), ethyl lactate using Cu-CLI, and pyruvic aldehyde using the Zn-BEA catalyst. In the case of a natural zeolite, modification with Sn is promising for obtaining a pure lactic acid with a relatively good carbon balance.

Cracking of the paraffins on catalysts from natural zeolite of Kazakhstan Shankanay field

Cracking of paraffins was held to obtain long chain α-olefins using the catalysts from natural zeolite of Shankanay field modified with 1N HCl at the temperature range of 500-570°С and atmospheric pressure on a fixed layer. Liquid and gaseous reaction products were analyzed by gas chromatography; regeneration of the catalyst was carried out with a steam-air mixture until total absence of CO2 in the contact gases. To evaluate the structure and texture of the obtained catalysts, the methods of Mössbauer spectroscopy, X-Ray diffractometry analysis, and elemental analysis using scanning electron microscopy were used. As results, zeolite modification allowed doubling the activity of the catalysts and increasing the selectivity by 23.8-44.8%. The group compositions of olefins, alkanes and gaseous products were detected. Iron form under α-Fe2O3, ε-FeOOH and γ-FeOOH was present. The modified and blank form of catalysts under 1N hydrochloric acid solution washing phase content was detected; partial destruction of the crystalline carcass of clinoptilolite was observed.

KAOLINITE MODIFIED BY ALUMINUM IN THE CRACKING OF VACUUM GASOIL AND IT’S MIXTURE WITH FUEL OIL

The data of the cracking of vacuum gas oil (VG) and a mixture of VG with fuel oil (M-100) on HLaY zeolite catalyst based on acid-activated kaolinite of the Pavlodar deposit modified by aluminum are presented. The synthesis of the kaolinite matrix and the HLaY zeolite catalyst with its use, the physicochemical and acid characteristics of the catalyst and its constituent components, and the fractional and hydrocarbon compositions of vacuum gas oil are described. High mesoporosity of the H-form of the used kaolinite (86.2%), modified by aluminum of the H-form (84.1) and the HLaY catalyst (80.1%), which provide the activity of the sample in cracking of the mixture with a yield of 32.6% gasoline and 25.9% light gas oil (LG) at 4500С and in cracking of VG a yield of 38.2% gasoline and 29.4% LG at 5000С. The gasolines of cracking of LG contain an increased content of iso paraffins (up to 20.2%) and a low content of aromatic hydrocarbons (24.1%), which makes the catalyst attractive for cracking a mixture of VG with fuel oil. Key words: catalytic cracking, kaolinite, vacuum gas oil, fuel oil, zeolite, modification.

Hydrophobic zeolite modification for in situ peroxide formation in methane oxidation to methanol

Selective partial oxidation of methane to methanol suffers from low efficiency. Here, we report a heterogeneous catalyst system for enhanced methanol productivity in methane oxidation by in situ generated hydrogen peroxide at mild temperature (70°C). The catalyst was synthesized by fixation of AuPd alloy nanoparticles within aluminosilicate zeolite crystals, followed by modification of the external surface of the zeolite with organosilanes. The silanes appear to allow diffusion of hydrogen, oxygen, and methane to the catalyst active sites, while confining the generated peroxide there to enhance its reaction probability. At 17.3% conversion of methane, methanol selectivity reached 92%, corresponding to methanol productivity up to 91.6 millimoles per gram of AuPd per hour.

Performance of Modified Natural Zeolites by Sodium Hydroxide Treatments in The Esterification of Glycerol and Oleic Acid

Esterification is the reaction of the formation of an ester compound by reacting an alcohol compound and carboxylic acid. In this study, the performance of zeolite-based catalysts has been studied for esterification reactions. Modification of zeolite pore size was done to be hierarchical zeolite, with the aim of increasing the catalytic properties of zeolite. The modification was carried out by desilication by sodium hydroxide treatment with a variation of 0.1; 0.3; 0.5 M. The resulting catalyst was then characterized using BET and XRD. Furthermore, the catalyst was tested for activity for esterification of fatty acids and glycerol and the product was analyzed using GC-MS. Zeolite modification with sodium hydroxide has been proven to improve catalyst performance, without changing their crystal structure. The best catalytic activity was obtained on the catalyst with sodium hydroxide treatment of 0.3 M, resulting glycerol conversion of 92% and selectivity to monoglycerides of 74%.