Dehydration of Biomass-derived Carbohydrates in a Biphasic Reactor using Cation Exchange Resin Catalyst for the Production of Hydroxymethylfurfural and Furfural

Biomass is a source of carbohydrates, which is composed of two different types of sugars hexose (glucose, galactose and mannose) and pentose (xylose and arabinose). These sugars can be dehydrated to produce platform chemicals like 5 - HMF (5 - hydroxymethylfur fural) and furfural. These are most promising chemicals because they are used in the production of fine chemicals, polymers and also starting materials for new products as well as for replacement of oil - derived chemicals. This work focuses on the productio n of 5 - HMF and Furfural by dehydration of fructose and xylose respectively. Dehydration of carbohydrates in aqueous phase can produce unwanted products because of side reactions such as rehydration, hydrolysis and condensation. To eliminate unwanted side r eactions an organic phase and inorganic salt were added to the system. Organic phase consisting of solvents which can extract the product from aqueous phase as it formed to eliminate the degradation of product and addition of salt to the reaction system wi ll increase the partition coefficient. Dehydration reaction was performed in a batch reactor over a cation exchange resin catalyst. Effect of reaction parameters such as temperature, time, and feed compositions were optimized to increase the yield. Effect of salt was studied and concluded that product concentration depends on salt concentration because of salting - out effect. Difference between using glucose and fructose to produce 5 - HMF was also studied and concluded that using fructose product concentrati on increased compared to the glucose. The reason behind this is dehydration of glucose can produce ene - diol intermediate which consists of unstable ring structure that can produce unwanted by products. So, glucose was initially isomerized to fructose and t hen dehydrated to produce 5 - HMF

Obtención de catalizadores ácidos a partir de la cascarilla de arroz

In this paper, is reported the development and utilization of silica from rice husk (rh) for the synthesis of solid acid catalysts. Sulfated zirconia catalysts were prepared by the sol–gel reaction, using an in situ sulfation. The parameter considered in this work was the Si/Zr molar ratio and the ultra sonication during the gelation time. Silicon precursor was obtained as sodium silicate by alkaline extraction from rice husk ash (rha) and zirconium were added into the silica matrix via sol-gel technique. Subsequently, the sulfation was done by adding suitable amounts of acid solutions. The catalyst was characterized by X-ray diffraction, nitrogen adsorption–desorption, and infrared spectroscopy. The results indicated that the catalyst have high bet surface area and crystalline structure. The acid catalysts activity was evaluated in the xylose dehydration reaction using water as solvent. The catalyst exhibited a catalytic potential in the furfural production.En este artículo se presenta la obtención de sílice a partir de la cascarilla de arroz, y su aplicación en la síntesis de catalizadores ácidos sólidos. Catalizadores de zirconio sulfatado soportado sobre sílice fueron obtenidos mediante la vía sol-gel usando una sulfatación in situ. Los parámetros considerados en esta investigación fueron la relación molar de Si/Zr y el uso de ultrasonido durante el tiempo de envejecimiento. El precursor de silicio fue obtenido en forma de silicato de sodio por medio de extracción alcalina de las cenizas de la cascarilla de arroz. Posteriormente, el zirconio fue adicionado en la matriz de sílice mediante la técnica sol-gel. Finalmente, la sulfatación fue llevada a cabo por la adición adecuada de ácido sulfúrico en solución. Los catalizadores fueron caracterizados por difracción de rayos X, adsorción-desorción de nitrógeno y espectroscopia de infrarrojo. Los resultados indican que los catalizadores tienen un área superficial BET considerable y estructura cristalina. La actividad catalítica fue evaluada en la reacción de deshidratación de xilosa usando agua como solvente. Los catalizadores mostraron un potencial catalítico en la producción de furfural

Conversion of d-xylose into furfural with aluminum and hafnium pillared clays as catalyst

The industrial practice used to produce furfural is the dehydration of pentoses, which is carried out using highly corrosive and contaminating mineral acid catalysts. Because of the ecological and toxicological threats of this process and the complexity of product separation associated with these substances, the development of new acid solid catalysts has expanded in recent years. The present work is focused on the production of furfural from D-xylose using aluminum and hafnium pillared clays as catalysts. After 4 h of reaction at temperatures ranging between 140 and 170°C, conversion rates of 50-80% were observed, and selectivity levels of 40-65% were reached. Finally, the stability of the catalyst was further investigated by applying a thermal treatment prior to reuse. A significant decrease in the selectivity was not observed in four consecutive reactions. Consequently the pillared clays appear to be active, selective and stable catalyst for pentose dehydrationEl proceso industrial utilizado para la producción de furfural es la deshidratación de pentosas, la cual se lleva a cabo por medio de ácidos minerales, altamente corrosivos y contaminantes como catalizadores. Debido a los efectos ecológicos y toxicológicos asociados a este proceso, y a la dificultad en la separación del producto, el desarrollo de nuevos catalizadores sólidos ácidos ha tenido una significativa expansión en los últimos años. El presente trabajo de investigación se enfocó en la producción de furfural a partir de D-xilosa empleando como catalizadores sólidos ácidos, arcillas pilarizadas con aluminio y hafnio. Después de 4 h de reacción a temperaturas entre 140 y 170 °C, los resultados evidenciaron una conversión entre el 50 y el 80%, mientras que los niveles de selectividad alcanzados estuvieron entre el 40 y el 65%. Finalmente, la estabilidad de los catalizadores fue evaluada por medio de un tratamiento térmico, antes de usarlo de nuevo. En cuatro reacciones consecutivas no fue observada una disminución significativa en la selectividad. En conclusión, las arcillas pilarizadas evidencian ser catalizadores activos, selectivos y estables para la deshidratación de pentosa

Conversion of d-xylose into furfural with aluminum and hafnium pillared clays as catalyst

The industrial practice used to produce furfural is the dehydration of pentoses, which is carried out using highly corrosive and contaminating mineral acid catalysts. Because of the ecological and toxicological threats of this process and the complexity of product separation associated with these substances, the development of new acid solid catalysts has expanded in recent years. The present work is focused on the production of furfural from D-xylose using aluminum and hafnium pillared clays as catalysts. After 4 h of reaction at temperatures ranging between 140 and 170°C, conversion rates of 50-80% were observed, and selectivity levels of 40-65% were reached. Finally, the stability of the catalyst was further investigated by applying a thermal treatment prior to reuse. A significant decrease in the selectivity was not observed in four consecutive reactions. Consequently the pillared clays appear to be active, selective and stable catalyst for pentose dehydration

The Development and Application of Microwave Heating

Microwave heating has found many applications ranging from the microwave ovens in kitchen to heat food, to a sterilization apparatus for medical treatment, to materials processing in the various fields. In those applications, microwave heating demonstrates significant advantages over conventional methods in reduced processing time and less environmental impacts. This book is comprised of eight chapters within three parts highlighting different aspects covering both the basic understandings and the advanced applications. The included discussion on the application of microwave heating in the field of food-, chemical engineering-, agricultural-, forestry- and mineral processing industry will provide a passage for future research. As a monograph, it is designed to be a fundamental reference book, aiming to help the readers to concentrate on the key aspects behind the success in microwave heating

Synthesis of new pyrazolium based tunable aryl alkyl ionic liquids and their use in removal of methylene blue from aqueous solution

In this study, two new pyrazolium based tunable aryl alkyl ionic liquids, 2-ethyl-1-(4-methylphenyl)-3,5- dimethylpyrazolium tetrafluoroborate (3a) and 1-(4-methylphenyl)-2-pentyl-3,5-dimethylpyrazolium tetrafluoroborate (3b), were synthesized via three-step reaction and characterized. The removal of methylene blue (MB) from aqueous solution has been investigated using the synthesized salts as an extractant and methylene chloride as a solvent. The obtained results show that MB was extracted from aqueous solution with high extraction efficiency up to 87 % at room temperature at the natural pH of MB solution. The influence of the alkyl chain length on the properties of the salts and their extraction efficiency of MB was investigated