Mohamed M. M. Abd El-Wahab

Arylidene polymers: Part 21. Thermal decomposition parameters of new diarylidenecycloalkanone organophosphorus polymers

Abstract A study of the non-isothermal decomposition of new aromatic polyphosphates (I–V) based on diarylidenecycloalkanone moieties has been carried out using TGA measurements at atmopsheric pressure. Analysis of non-isothermal TG and DTG curves of these polyphosphate esters indicated that their decompositions proceed in three stages. Kinetic parameters such as activation energy (Ea), pre-exponential factor (A) and entropy of activation (ΔS∗) for the whole samples at different decomposition stages are determined. The data showed that the thermal stability of polymers I–III decreases with increasing ring size of the diarylidenecycloalkanone moieties. The effect of the presence of -OCH3 groups upon the thermal properties of polymers is also discussed.

Selective synthesis of acetone from isopropyl alcohol over active and stable CuO–NiO nanocomposites at relatively low-temperature

Abstract CuO–NiO nanocomposite catalysts were synthesized by an oxalate precipitation route. The basicity of the catalysts was measured using adsorption–desorption of acetic acid. The catalytic conversion of isopropanol to acetone was carried out in a conventional fixed bed flow type reactor at 200 °C using N2 as a carrier gas. The results indicated that, the addition of NiO to CuO greatly enhanced the electrical conductivity via the creation of new charge carriers (Cu+–Ni3+). In addition, the results revealed that the catalyst containing 30 wt.% NiO calcined at 400 °C possesses the highest catalytic activity with 98% conversion and 100% selectivity to acetone. The remarkable catalytic performance of the synthesized catalysts is attributed to the decrease of the energy gap, the increase in the concentration of charge carries (Cu+–Ni3+), and to the creation of more weak and intermediate basic sites.

Arylidene Polymers—XXII. Thermogravimetric and Kinetic Analyses of Non-isothermal Decomposition of Organometallic Arylidene Polyester

Studies of non-isothermal decomposition of certain iodo-organometallic arylidene polyesters and organometallic arylidene polyesters have been performed with TGA measurements at atmospheric pressure. The analysis of the non-isothermal TG and DTG curves of the samples under investigation revealed that their decomposition course proceeds via three stages. The kinetic parameters such as activation energy (E,), preexponential factor (A) and entropy of activation (AS*) for all polymers at different decomposition stages are determinedfrom an appropriate kinetic equation. More particularly, the data showed that the thermal stability of some of the polymers decreases with increasing ring size of arylidene moieties. Furthermore, the effect of absence of iodoand presence of-OCH3 groups upon the thermal properties of polymers was also evaluated.