Sustainable Catalytic Process for Synthesis of Triethyl Citrate Plasticizer over Phosphonated USY Zeolite

Fruits wastage is harmful to health and environment concerning spreading diseases and soil pollution, respectively. To avoid this issue, use of citrus fruit waste for the production of citric acid (CA) is one of viable mean to obtain value added chemicals. Moreover, synthesis of triethyl citrate (TEC), a non-toxic plasticizer by esterification of CA with ethanol over heterogeneous catalyst would be renewable and sustainable catalytic process. In this context, parent Ultrastable Y (USY) and different percentage phosphonated USY (P-USY) zeolites were used for the synthesis of TEC in a closed batch reactor, for the first time. The synthesized catalysts were characterized by N2-adsorption desorption isotherm, powder X-ray diffraction (XRD) and NH3 temperature programmed desorption (TPD. Effect of reaction conditions, such as the molar ratio of ethanol to CA (5:1 - 20:1), the catalyst to CA ratio (0.05 - 0.25) and reaction temperature (363-403 K), were studied in view to maximizing CA conversion and TEC yield. Phosphonated USY catalysts were found to be superior in activity (CA conversion and TEC yield) than parent USY, which is attributed to the increased in total acidity with phosphonation. Among the studied catalysts, the P2USY (2% phosphorous loaded on USY) was found to be an optimum catalyst with 99% CA conversion and 82% TEC yield, which is higher than the reported values. This study opens new avenues of research demonstrating principles of green chemistry such as easy separable and reusable catalyst, non-toxic product, bio-renewable synthetic route, milder operating parameters and waste minimization.

Рутениевые катализаторы на углеродном носителе с контролируемым размером частиц для селективного гидрирования левулиновой кислоты в γ-валеролактон

Liquid phase levulinic acid hydrogenation into γ-valerolactone in 1,4-dioxane as a solvent (165°C, 20 bar) was studied over a range of Ru monometallic catalysts using mesoporous carbon material Sibunit as a support. In addition to the catalyst prepared by impregnation with RuCl3∙nH2O (0.1 M) followed by reduction in H2, size-controlled Ru(NPs)/Sibunit catalysts were synthesized by immobilization of polyvinylpyrrolidone (PVP) stabilized Ru nanoparticles (NPs) (dRu=2.4 nm). Сarbon supported colloidal Ru NPs were not studied earlier in levulinic acid hydrogenation. Activity of colloidal Ru(NPs)/Sibunit catalysts was found to be lower than that of impregnated Ru/Sibunit which could be attributed to hampering effect of PVP. However, colloidal Ru(NPs)/Sibunit purified by thermal treatment in air (180°C) followed by reduction in H2 (400°C) exhibited the same activity as impregnated one yielding 93% γ-valerolactone at 100% levulinic acid conversion. Applicability of supported PVP-assisted colloidal Ru NPs in hydrogenation of levulinic acid illustrates a potential to prepare more efficient catalysts for this reaction with a desired particle size. The catalysts were characterized by TEM, XRF, and N2 physisorption to compare their physical chemical propertiesЖидкофазное гидрирование левулиновой кислоты (ЛК) в γ-валеролактон (ГВЛ) было изучено в присутствии Ru на мезопористом углеродном носителе Сибунит (растворитель 1,4-диоксан, 165 °C, давление водорода 20 бар). Наряду с катализаторами, приготовленными методом пропитки раствором RuCl3 nH2O (0,1 М) с последующим восстановлением в Н2, были синтезированы катализаторы Ru/Сибунит с контролируемым размером частиц Ru путем иммобилизации стабилизированных поливинилпирролидоном (ПВП) наночастиц (НЧ) Ru (dRu 2,4 нм), ранее не исследованные в гидрировании ЛК. Показано, что активность коллоидных Ru(НЧ)/Сибунит ниже, чем у пропиточных, что может быть обусловлено блокирующим эффектом ПВП. Обработка на воздухе (180 °C) с последующим восстановлением в водороде (400 °C) приводит к увеличению активности Ru(НЧ)/Сибунит до активности пропиточного Ru/Сибунит с селективностью 93 % по ГВЛ при 100%-й конверсии ЛК. Эффективность ПВП- стабилизированных коллоидных НЧ Ru в гидрировании ЛК открывает возможность получения более эффективных катализаторов для этой реакции с контролируемым размером частиц. Катализаторы изучены методами ПЭМ, РФлА и адсорбции азот

Valorisation of Biowastes for the Production of Green Materials Using Chemical Methods

With crude oil reserves dwindling, the hunt for a sustainable alternative feedstock for fuels and materials for our society continues to expand. The biorefinery concept has enjoyed both a surge in popularity and also vocal opposition to the idea of diverting food-grade land and crops for this purpose. The idea of using the inevitable wastes arising from biomass processing, particularly farming and food production, is, therefore, gaining more attention as the feedstock for the biorefinery. For the three main components of biomass—carbohydrates, lipids, and proteins—there are long-established processes for using some of these by-products. However, the recent advances in chemical technologies are expanding both the feedstocks available for processing and the products that be obtained. Herein, this review presents some of the more recent developments in processing these molecules for green materials, as well as case studies that bring these technologies and materials together into final products for applied usage

Novelties of heteropoly acid supported on clay: etherification of phenethyl alcohol with alkanols

Dodecatugstophosphoric acid, a heteropoly acid supported on K-10 which is a montmorillonite clay, has been found to be a very efficient and novel catalyst in comparison with several others in the etherification of phenethyl alcohol with a variety of alkanols. The reactions are 100% selective towards the formation of the ethers which aresignificantly used in the perfumery industry. The experimental data demonstrate that the chemisorption of phenethyl alcohol onto the catalytic site controls the overall rate of reaction for all etherification reactions with methanol, ethanol, isopropanol and isopentanol. An Eiley-Rideal type of mechanism prevails

Transesterification of edible and nonedible vegetable oils with alcohols over heteropolyacids supported on acid-treated clay

In the current work, the novelty of heteropolyacid on clay (K-10) for the transesterification of vegetable oil with lower and higher alcohols is presented. Methyl esters (biodiesel) and glycerol were produced by the transesterification of vegetable oil with methanol in the presence of dodecatungestophosphoric acid (DTPA) supported on K-10 clay. The transesterification consists of three consecutive reversible reactions. Diglycerides (DG) and monoglycerides (MG) are intermediate products. The optimal catalyst concentration was 5% w/w of oil. Detailed studies were done for optimization of the process parameters. The rate of transesterification in a batch reactor increased with temperature up to 170 °C. Higher temperatures did not reduce the time to reach maximum conversion. The study was also extended to reactions of different edible and nonedible oils with lower and higher alcohols. The conversion of TG, DG, and MG seemed to be a second-order mechanism for the forward and reverse reactions, where the reaction system could be described as a pseudo-heterogeneous catalyzed reaction. The reaction rate constants for the TG, DG, and MG transesterification reactions were 0.12−0.84 h−1 and were higher for the MG reaction than for the TG transesterification. The activation energies were 4.2, 26, and 7.4 kcal/mol for the TG, DG, and MG transesterification reactions, respectively. The proposed kinetic model fits the experimental results well

Synthesis of pharmaceutical intermediates by toluene benzylation over heteropoly acids on different support

Selective formation of pharmaceutical intermediates like diphenylmethane, dimethyl-diphenylmethane, benzyl toluene and benzole acid by liquid phase, toluene benzylation with benzyl chloride as a benzylating agent, was systematically studied over plane clay (K-10, montmorillonite), plane H-Beta, plane MFI structured titanosilicate (TS-1) and heteropoly acids [HPA, namely dodeca-tungstophosphoric acid [H3PO4·-12WO3·x H2O] (TPA), dodeca-molybdo phosphoric acid ammonium salt hydrate [H12Mo12N3O40P+aq] (DMAA), sodium tungstate hydrated purified [Na12WO4-2H2O] (STH)] supported on clay, H-beta and TS-1. The 20%TPA/Clay, 30%TPA/H-Beta and 30%TPA/TS-1, were observed to be the best catalyst samples over plane clay, plane H-Beta and plane TS-1. The catalyst samples are compared with respect to benzyl chloride conversion and selectivities for diphenylmethane, dimethyl-diphenylmethane, benzyl toluene and benzole acid. The reaction follows the pseudo-first order rate power law model. The apparent rate constants are calculated and compared with the reported ones

Synthesis of bio-diesel and bio-lubricant by transesterification of vegetable oil with lower and higher alcohols over heteropolyacids supported by clay (K-10)

The use of different lower and higher alcohols viz; methanol, ethanol, n-propanol and n-octanol, for the synthesis of methyl, ethyl, propyl and octyl fatty acid esters by transesterification of vegetable oil (triglycerides) with respective alcohols also known as ‘Bio-diesel’ and ‘Bio-lubricants’ was studied in detail. The reactions were carried out in a batch process. The activity with different supports like clay (K-10), activated carbon, ZSM-5, H-beta and TS-1 were compared. The superacids (heteropolyacids, HPA) viz; Dodeca-Tungstophosphoric acid [H3PO4·12 WO3·xH2O] (TPA) and Dodeca-Molybdo phosphoric acid ammonium salt hydrate [H12Mo12N3-O40P + aq] (DMAA) was used to increase the acidity and so the activity by loading on the most active support viz; clay (K-10). These HPA loaded on clay as a catalyst was used for the following study: effect of percent HPA loading on clay, effect of different vegetable oils, effect of different alcohols on the triglyceride conversion based on glycerol formation and selectivity based on alkyl esters formation. The data is compared at the best-optimized identical set of operating reaction conditions: 170 °C, 170 rpm, catalyst loading: 5% (w/w of reaction mixture), molar ratio (oil: alcohol): 1:15 and time on stream of 8 h. The generated data is also evaluated based on the reported one

Heteropolyacid supported on montmorillonite catalyst for dehydration of dilute bio-ethanol

Vapour phase dehydration of dilute bio-ethanol (EtOH) to ethylene (E) and diethyl ether (DEE) is industrially relevant. Ethylene is an important raw material for many petrochemical products and Diethyl ether (DEE) can be used as an alternative fuel. The efficacy of montmorillonite (K-10) and dodecatungestophosphoric acid (DTPA) supported on montmorillonite (DTPA/K-10), has been evaluated in the current work in the dehydration of dilute bio-ethanol (80% m/m). The dehydration of ethanol and cracking of diethyl ether were studied independently. 30% m/m DTPA/K-10 was found to be more active with 74% ethanol conversion and 92% ethylene selectivity at 250 °C in comparison with other acid catalysts used. The merit of the process lies in its use of dilute bio-ethanol, a new avenue for ethylene production from a non-petroleum feedstock. Kinetic interpretation has been made by studying the important process parameters by using 30% m/m DTPA/montmorillonite as the catalyst. The mechanism of the dehydration of ethanol reaction suggests that two types of sites are responsible. The dehydration of ethanol and cracking of diethyl ether are second order reactions with weak adsorption of species