Sat Parkash

Thermal decomposition of asphaltenes

Abstract The thermal decomposition of Athabasca asphaltene at relatively low ( 350 °C) temperatures are attained.

Microporosity in Alberta Plains coals

Abstract The nature of porosity in 11 Alberta Plains coals is scanned using different characterization techniques, namely, gas adsorption, helium and mercury displacement, and mercury porosimetry. Surface areas calculated from carbon dioxide adsorption at 25°C (varying between 75 and 506 m 2 /g) are consistently higher than those calculated from nitrogen at −196°C (varying between 1 and 9 m 2 /g). The samples from Paskapoo deposits have slightly higher surface areas as compared to samples from Horseshoe Canyon deposits. The carbon content in the tested coals (73.4 to 76.8%) is too narrow of range to determine the influence of this parameter on surface area and porosity. Total pore volumes are measured in the range 1.2 to 3000 nm and then divided into macropores (30 to 3000 nm), transitional pores (1.2 to 30 nm) and micropores (less than 1.2 nm). Almost all the surface area in coals is located in the micropores. Coals vary widely in their total pore volumes and porosities range between 9.5 and 22.3%. Percent pore volume contained in micropores varies between 29.5 and 75.9, in transitional pores between 1.1 and 20.5 and in macropores between 18.5 and 50.0.

Physical properties and surface characteristics of asphaltenes

The pore structure of asphaltenes is investigated by N2 adsorption at 77 K, density measurements in helium at 298 K and determination of the penetration of mercury at high pressures. The results indicate that pore sizes fall into two groups, those > 200 nm (wide macropores) and those < 1.5 nm (fine micropores) which may be considered as being inherent to the molecular structure of asphaltenes. Paramagnetic resonance data show a relation between spin numbers and carbon content and the various atomic ratios.

Petrography of low rank coals with reference to liquefaction potential

Abstract Ten sub-bituminous coals were analyzed petrographically and chemically as part of a program by the Alberta Research Council to investigate the compositional properties of Alberta coals and relationship to liquefaction potential. In addition, four lignites, two from Saskatchewan and one each from Texas and North Dakota, were studied for comparative purposes. Liquefaction experiments were carried out on three of the Alberta coals and on density fractions of the two U.S. lignites. Petrographically the ten sub-bituminous coals could be divided into two populations; one with high huminite and liptinite contents (>90%) and one with substantially lower contents (70–75%). The two U.S. lignites showed huminite plus liptinite contents of less than 70% while the Saskatchewan coals were somewhat higher. Reflectance measurements on the sub-bituminous coals showed a range of 0.33 to 0.51 with a rough correlation to the ASTM rank designations of these coals. Reflectivities determined on the lignites were generally lower. Float-sink fractionation of the two U.S. lignites and two sub-bituminous coals showed enrichment of huminite and liptinite in the lighter fractions and inertinite and mineral matter in the heavier splits. Examination of the relationship between liquefaction yields and petrographic composition showed a rough positive correlation with huminite-liptinite content. Examination of liquefaction residues suggested total conversion of the liptinite, extensive conversion of huminite and possible partial conversion and reactivity of the semifusinite maceral of the inertinite group.

True density and elemental composition of subbituminous coals

Abstract Multivariate correlation, indicating strong dependence of coal density on elemental composition, expressed on a dry, ash-free basis [ ρ He = 3.5742 − (0.0197 C + 0.0192 O ) − 0.0691 H ] is proposed for low-rank coals (C, 70.8–75.8 wt%; reflectance 0.24–0.48%), maceral concentrates and chars produced (550–700 °C) from subbituminous coals. True densities calculated using the above expression account for 83% of the variance of the measured densities (by helium pycnometry) of low-rank coals and their macerai concentrates and chars and 75% for US coals of different ranks.

Petrographic composition and liquefaction behaviour of North Dakota and Texas lignites

Abstract Two US lignites (from Texas and North Dakota) were fractionated by density with appropriately prepared mixtures of liquid halogenated and non-halogenated hydrocarbons. Petrographic analyses confirmed that the procedure resulted in density fractions enriched in specific macerals. Liquid yields obtained upon solubilization at 430 °C and 5.5 MPa hydrogen pressure decreased with increase in the density fraction for both lignites. On plotting the total solubilities of lignites and their density fractions versus their huminite contents a reasonably good linear correlation was obtained (particularly for North Dakota lignite). It is tentatively concluded that in North Dakota lignite, as opposed to Texas lignite, macerals other than huminite did not significantly contribute to generation of liquid products.

Contribution of vitrinite macerals to the liquefaction of subbituminous coals

Abstract Four Alberta subbituminous coals were selected to investigate the contribution of vitrinite macerals to liquefaction. There are indications of a rectilinear correlation between conversion yields of different density fractions of coal and their vitrinite content, but it is too early to discern any conversion factor by which any maceral group may be used to predict the liquefaction behaviour of a subbituminous coal. Contrary to common belief, not all the vitrinite fraction of the feed coal is reactive. There seems to be a definite positive correlation between the percent vitrinite reacted and the liquefaction conversion yield. Much more research work is needed to further understand the contribution of vitrinite macerals to liquefaction of a subbituminous coal.

The role of acid-base sites in the preparation of Al2O3-supported platinum catalysts

Abstract The sorption of hexachloroplatinic acid on variously prepared specimens of alumina has been investigated under equilibrium and kinetic conditions. Relationships between metal dispersibility and sorption are interpreted in terms of interactions with surficial acid-base couple sites on the alumina substrates.

Effects of boron trifluoride sorption on the caking properties of coal

Abstract Reversible and irreversible sorption of boron trifluoride by a suite of low- and medium-volatile bituminous (caking) coals was investigated. Extraction of irreversibly sorbed BF 3 with diethyl ether was used to test the hypothesis that BF 3 interacts with coal by forming adducts. An approximately rectilinear but inverse relation between residual sorbed BF 3 and the free swelling index was found.

Changes in the physical structure of coal on partial solubilization

Abstract Changes in the physical structure of Alberta hvCb coal upon partial solubilization in tetralin, Athabasca bitumen and the oil fraction from the bitumen were determined from gas adsorption measurements, mercury porosimetry and petrographic examination. It was shown that solubilization of the coal generated new micropores, while the macropore structure was degraded. Resistance to extraction due to pore structure is considered to be probably of minor importance. The experimental results suggest that low molecular weight material in the coal was preferentially liquefied.