Influence of Phosphoric Acid Modification on Catalytic Properties of γ-χ Al2O3 Catalysts for Dehydration of Ethanol to Diethyl Ether

In this present work, diethyl ether, which is currently served as promising alternative fuel for diesel engines, was produced via catalytic dehydration of ethanol over H3PO4-modified g-c Al2O3 catalysts. The impact of H3PO4 addition on catalytic performance and characteristics of catalysts was investigated. While catalytic dehydration of ethanol was performed in a fixed-bed microreactor at the temperature ranging from 200ºC to 400ºC under atmospheric pressure, catalyst characterization was conducted by inductively coupled plasma (ICP), X-ray diffraction (XRD), N2 physisorption, temperature-programmed desorption of ammonia (NH3-TPD) and thermogravimetric (TG) analysis. The results showed that although the H3PO4 addition tended to decrease surface area of catalyst resulting in the reduction of ethanol conversion, the Al2O3 containing 5 wt% of phosphorus (5P/Al2O3) was the most suitable catalyst for the catalytic dehydration of ethanol to diethyl ether since it exhibited the highest catalytic ability regarding diethyl ether yield and the quantity of coke formation as well as it had similar long-term stability to conventional Al2O3 catalyst. The NH3-TPD profiles of catalysts revealed that catalysts containing more weak acidity sites were preferred for dehydration of ethanol into diethyl ether and the adequate promotion of H3PO4 would lower the amount of medium surface acidity with increasing catalyst weak surface acidity. Nevertheless, when the excessive amount of H3PO4 was introduced, it caused the destruction of catalysts structure, which resulted in the catalyst incapability due to the decrease in active surface area and pore enlargement. Copyright © 2019 BCREC Group. All rights reservedReceived: 28th March 2018; Revised: 7th August 2018; Accepted: 15th August 2018; Available online: 25th January 2019; Published regularly: April 2019How to Cite: Limlamthong, M., Chitpong, N., Jongsomjit, B. (2019). Influence of Phosphoric Acid Modification on Catalytic Properties of g-c Al2O3 Catalysts for Dehydration of Ethanol to Diethyl Ether. Bulletin of Chemical Reaction Engineering & Catalysis, 14 (1): 1-8 (doi:10.9767/bcrec.14.1.2436.1-8)Permalink/DOI: https://doi.org/10.9767/bcrec.14.1.2436.1-8

Surface Modification of Poly (M-Phenylene isophthalamide) Fibers and its Effect on the Mechanical Properties of Aramid Sheets

In order to improve the bonding properties between poly (m-phenylene isophthalamide) (PMIA) fibers and PMIA-pulp and to improve the mechanical strength of aramid sheets, PMIA fibers have been treated with various chemical modifying agents. The surface morphology of the treated fibers has been analyzed and the mechanical properties of aramid sheets made from the treated PMIA fibers and PMIA-pulp have been investigated. The results show that silane coupling agent modification, phosphoric acid modification and nitrification/reduction modification of PMIA fibers are all helpful for improving the tensile strength and tear strength of aramid sheets, however, they have different effect on the mechanical strength of aramid sheets, and the concentration of chemical modifying agents also has considerable influence on the surface properties of aramid fibers and the mechanical properites of aramid sheets. Aramid handsheets made from PMIA fibers treated with 20% phosphoric acid have the highest mechanical strength, and the tensile strength and tear strength of them are 23.4% and 31.6% higher than that of aramid handsheets made from untreated fibers, respectively, because the treated fiber surface has more oxygenous functional groups and is more rough than the untreated fiber surface.