Adnan M. Al-Amer

Catalytic cracking of polyethylene over all-silica MCM-41 molecular sieve

Abstract The catalytic cracking of high-density polyethylene has been demonstrated over all-silica MCM-41 catalysts. The cracking activity increases with the degree of crystallinity of the catalysts. The pore diameter of the samples has an effect on the level of the catalytic activity, with catalysts having small pore diameters giving higher activity. A carbenium ion-mediated mechanism is proposed for the cracking reaction, as high levels of isobutene and isobutane and low levels of C 1 and C 2 were produced. The product distribution was compared with those obtained from thermal cracking tests. The surface acidity of the all-silica MCM-41 is attributed to the presence of silanol groups. It is proposed that the formation and stabilization of carbenium ions in the pores of the catalyst are due to the adsorption interaction between the polyethylinic fragments with the surface of the channels.

OXIDATIVE DEHYDROGENATION OF PROPANE

The oxidative dehydrogenation of propane provides a highly selective catalyst for the oxidative dehydrogenation of propane to propylene, and a process for preparing the catalyst. The catalyst is a mixed metal oxides catalyst of the general formula MoaVbOx, where the molar ratio of molybdenum to vanadium is between 1:1 and 9:1 (a:b is between 0.5:0.5 and 0.9:0.1) and x is determined according to the oxidation state of the cations present. The catalyst is prepared by mixing the metals by sol-gel technique, heating the gel to dry the mixed oxides, further heating the dried product to induce auto-combustion, washing the product with isopropyl alcohol, and drying with a supercritical CO2 dryer. Oxidative dehydrogenation is carried out by contacting a stream of propane gas with the bulk mixed metal oxides catalyst at a temperature between 350° C. and 550° C. Propylene selectivity of 100% is reached at conversion rates between 1.9% and 4.8%.At temperatures near 650°C and residence times ofca. 3 s, the homogeneous oxidative dehydrogenation (OXD) of propane to propylene and ethylene approached oxygen limiting conditions, even when the reactor was filled with quartz chips. The addition of catalysts that are known to be effective in the OXD of ethane slightly increased the reaction rate, but the selectivities at a given conversion level were the same as those that were achieved in the homogeneous reaction.

An optimization model for guiding the petrochemical industry development in Saudi Arabia

A mixed integer linear programming model is formulated for determining the optimum plan for the expansion of the Saudi Arabian petrochemical industry. The products selected for consideration fall into four categories: propylene derivatives, ethylene derivatives, synthesis gas derivatives, and aromatic derivatives. The model incorporates new variables and constraints, and realistic estimates of production costs, which are calculated based on local conditions in Saudi Arabia. For each production process, the unit production cost is assumed to be a function of production capacity. The input data for each product includes relevant production technologies, capacities, local production costs, and selling price. The solution of the model gives the recommended products under different scenarios of available capital investment and feedstock. The results are reported and analyzed.

Radiation Vulcanization of Natural Rubber Latex Loaded with Carbon Nanotubes

The radiation vulcanization of natural rubber latex (NRL) has been carried out with 150 keV electrons beam with the presence of carbon nanotubes. The NRL/CNTs were prepared by using solving casting method by dispersing carbon nanotubes in a polymer solution and subsequently evaporating the solvent. The load of the carbon nanotubes in the rubber was varied from 1–7wt%. Upon electron beam irradiation, the tensile modulus of the nanocomposites increases with the increase of carbon nanotubes content up to 7wt%. The nanotubes were dispersed homogeneously in the SMR‐L matrix in an attempt to increase the mechanical properties of these nanocomposites. The properties of the nanocomposites such as tensile strength, tensile modulus, tear strength, elongation at break and hardness were studied.

Mechanical, Rheological and Thermal Properties of Polystyrene/1-Octadecanol Modified Carbon Nanotubes Nanocomposites

The results of the studies on the functionalization of multi-walled carbon nanotubes (MWCNT) with 1-octadecanol and its usage as reinforcing filler in the bulk polymerization of styrene are reported in this article. Both unmodified and modified CNTs were utilized in different loadings, however, without any initiator. The resulting composites were characterized by using mechanical testing, differential scanning calorimetry, thermogravimetric analysis and melt rheology. The tensile tests show the addition of 0.5wt% of CNT-C18 results in 19.5% increment of Youngs modulus. The DSC study shows a decrease in Tg values of prepared PS/CNT nanocomposite. The rheological study was conducted at 190°C and shows that addition of pure CNT increased the viscoelastic behavior of the PS matrices, while the CNT-C18 act as plasticizer. Thermogravimetric analysis shows that the incorporation of CNT into PS enhanced the thermal properties significantly.

Xylenes transformation over ZSM-5 zeolite in a fluidized-bed reactor

The transformation of xylenes have been investigated over ZSM-5 zeolite using a fluidizedbed reactor. The sequence of xylenes reactivity is found to decrease as follows: p-xylene > o-xylene > m-xylene. o-Xylene transformation exhibits the highest isomerization/disproportionation (I/D) ratio, which decreases rapidly with reaction temperature. p-Xylene selectivity is found to be enhanced at lower reaction temperature. The value of m-xylene/o-xylene (M/O) ratio obtained with p-xylene conversion is higher than the equilibrium value in the initial stage of the reaction. The obtained results indicate higher isomerization selectivity as compared to disproportionation during the conversion of the three xylene isomers.

PRELIMINARY SELECTION OF POLYMERIC ENTRAINERS FOR THE AZEOTROPIC DISTILLATION OF MTBE/METHANOL AND ETHANOL/WATER MIXTURES USING THE UNIFAC GROUP-CONTRIBUTION CALCULATIONS METHOD

*Previous publications by the author appeared under his sub-family name of Al-Jarallah. In this work the UNIFAC group-contribution calculations method was used to determine relative volatility in the presence of selected polymeric entrainers at different weight fractions in ethanol/water and methyl tertiary butyl ether/methanol systems. To quantify the effect of the added polymers, the ratio of relative volatility with and without the polymer was calculated. The purpose of these calculations was to identify the systems that have ratios of relative volatility distinct from unity because they may indicate polymers with the ability to break the azeotrope. This information should guide the initial selection of potential polymers capable of breaking the azeotrope and thus save time and effort. The results of these calculations are reported. Because these polymers must be soluble in the system, solubility tests were performed and the results are reported. Comparison of these predictions with previously published experimental vapor-liquid equilibrium data for the same systems gave conflicting results: Some predictions were confirmed and others were not. Thus, the UNIFAC group-contribution calculations were not always reliable in predicting relative volatility. More accurate group-contribution methods would make the polymer design more reliable.*Previous publications by the author appeared under his sub-family name of Al-Jarallah. In this work the UNIFAC group-contribution calculations method was used to determine relative volatility in the presence of selected polymeric entrainers at different weight fractions in ethanol/water and methyl tertiary butyl ether/methanol systems. To quantify the effect of the added polymers, the ratio of relative volatility with and without the polymer was calculated. The purpose of these calculations was to identify the systems that have ratios of relative volatility distinct from unity because they may indicate polymers with the ability to break the azeotrope. This information should guide the initial selection of potential polymers capable of breaking the azeotrope and thus save time and effort. The results of these calculations are reported. Because these polymers must be soluble in the system, solubility tests were performed and the results are reported. Comparison of these predictions with previously publishe...