Siauw H. Ng

Fractal analysis of gas adsorption on Syncrude coke

Abstract Fractal dimension is an intrinsic, quantitative measure of surface irregularity and provides a convenient parameter for comparing surface physical properties. Several particle size ranges of Syncrude coke were studied by nitrogen and carbon dioxide adsorption. The apparent surface area, A, was observed to increase from 1 to 15 m2 g−1 for N2 and from 65 to 300m2 g−1 for CO2 data with decreased particle size. The fractal dimension, D, was determined from the proportionality: A∝RD-3, where the surface area is determined by BET or D-P (Dubinin-Polanyi) theories, R is the particle radius and 2⩽D⩽3. The value of D for Syncrude coke was determined to be 2.48 from both N2 and CO2 results.

RemaRks on VaRious applications of micRowaVe eneRgy

Microwave energy is an alternative energy source that is receiving a considerable amount of attention from researchers for a wide spectrum of applications. The fundamentally different method of transferring energy from the source to the sample is the main benefit of utilizing microwave energy; by directly delivering energy to microwave-absorbing materials, conventional issues such as long heating periods, thermal gradients, and energy lost to the system environment can be minimized or avoided. Furthermore, the penetrating capacity of microwave allows volumetric heating of samples. These attributes of microwave energy make utilizing it very attractive for industrial applications as an alternative to conventional processing methods. The reality is otherwise however, and limited literature is found in any given area of work. Despite the lack of focus, in most published cases, the utilization of microwave energy has produced improved results compared to conventional methods with reduced heating times or reaction temperatures. This review provides a general overview of reported applications of microwave energy in the open literature. It also attempts to summarize the results obtained for various common uses and highlights some applications that have not gathered as much attention as anticipated.

Study of the pore structure and reactivity of Canadian coal-derived chars

Abstract The pore volume, surface area, compressibility and reactivity of 12 chars derived from Canadian coals ranking from lignite to anthracite, have been determined by mercury porosimetry, gas adsorptiondesorption with N 2 and CO 2 adsorbates, helium and mercury densities and thermogravimetric technique. A comparison of the pore structure between the chars and their parent coals was made based on the results obtained from these techniques. The reactivity of chars was correlated with their physical and chemical properties. It has been found that a single relationship exists between the helium density and the carbon content of the coals and their chars. The chars are more porous but less compressible when compared with their parent coals.

Surface structure and oxidation reactivity of oil sand coke particles

Abstract Fractions of particles of varying mean diameter were isolated from coke obtained from the fluid coking of Athabasca bitumen. Correlations were established between the rate of oxygen sorption and the apparent surface area as measured by carbon dioxide adsorption. The rate of oxygen sorption, r0, could be related to particle radius, R, by the equation: r0 ∝ RD − 3 over a range of particle size where D is the fractal dimension of the coke. The existence of such correlations may be related to the iterative processes which form the particles.

Evaluation of deasphalted heavy oil residues as catalytic cracking feed using a riser kinetic model

Abstract A novel fluid catalytic cracking (FCC) unit simulator is used to compare the performance of solvent deasphalted heavy oil residues with that of conventional gas oils, under commercial heat balanced unit operating conditions. The simulations are based on rate constants for cracking, gasoline formation and catalyst activity decay derived from laboratory measurements made with a small volume fixed bed reactor. Results from the simulations confirm the acceptability of deasphalted residues as FCC feeds, subject to defined modification of the unit operating conditions.

Microwave-assisted conversion of ethane to ethylene

A novel microwave reactor has been constructed for the conversion of ethane to ethylene. The bench-top, pilot-scale facility is capable of conventional furnace heating and microwave-assisted heating, thus allowing direct comparative studies between the conventional industry-wide process and the novel microwave-assisted conversion process. The latter makes use of chemical substances called susceptors that are good microwave absorbers and can transfer heat energy to the surrounding environment. The ethane feed stream is thus heated to achieve thermal conversion to ethylene. Data validating the apparatus and preliminary data on the feasibility of conversion are presented.

Laboratory Production of Biofuels and Biochemicals from a Rapeseed Oil through Catalytic Cracking Conversion

The work is based on a reported study which investigates the processability of canola oil (bio-feed) in the presence of bitumen-derived heavy gas oil (HGO) for production of transportation fuels through a fluid catalytic cracking (FCC) route. Cracking experiments are performed with a fully automated reaction unit at a fixed weight hourly space velocity (WHSV) of 8 hr(-1), 490-530 °C, and catalyst/oil ratios of 4-12 g/g. When a feed is in contact with catalyst in the fluid-bed reactor, cracking takes place generating gaseous, liquid, and solid products. The vapor produced is condensed and collected in a liquid receiver at -15 °C. The non-condensable effluent is first directed to a vessel and is sent, after homogenization, to an on-line gas chromatograph (GC) for refinery gas analysis. The coke deposited on the catalyst is determined in situ by burning the spent catalyst in air at high temperatures. Levels of CO2 are measured quantitatively via an infrared (IR) cell, and are converted to coke yield. Liquid samples in the receivers are analyzed by GC for simulated distillation to determine the amounts in different boiling ranges, i.e., IBP-221 °C (gasoline), 221-343 °C (light cycle oil), and 343 °C+ (heavy cycle oil). Cracking of a feed containing canola oil generates water, which appears at the bottom of a liquid receiver and on its inner wall. Recovery of water on the wall is achieved through washing with methanol followed by Karl Fischer titration for water content. Basic results reported include conversion (the portion of the feed converted to gas and liquid product with a boiling point below 221 °C, coke, and water, if present) and yields of dry gas (H2-C2s, CO, and CO2), liquefied petroleum gas (C3-C4), gasoline, light cycle oil, heavy cycle oil, coke, and water, if present.