Bituminous polyurethane network: Preparation,properties, and end use

Industrial‐grade bitumen (85:25) was treated with 4,4′‐diphenyl methane diisocyanate as a blocking agent to make it compatible with polyurethane resin. Optimization of treatment conditions for the bitumen such as isocyanate dose (～3 wt % of bitumen), reaction temperature (180°C), and treatment time (120 min) was done on the basis of estimating its residual acid value and unreacted ? NCO groups. Formation of the urethanized bituminous species after treatment resulted in a reduction in the glass‐transition temperature of the base bitumen from ?9.63°C to ?17.09°C and in moisture vapor transmission from 16.95 to 12.21 g 24 h^?1 m^?2. The bituminous networks were prepared from these treated/SBS‐modified treated bitumen and polyurethane prepolymers by in situ and conventional liquid blending methods. Lack of low‐temperature flexibility in the bituminous network made from the blending method restricted its use for waterproofing/sealing purposes. Modulated differential scanning calorimetry showed the presence of two overlapping glass‐transition temperatures and an endothermic peak in the in situ prepared networks similar to the base bitumen, evidence of a close intermixing of the bitumen constituents with the polyurethane phases. Rheological studies revealed that the SBS‐modified bituminous polyurethane network exhibited superior behavior than that of other systems in terms of stiffness and elasticity over a wide range of frequencies. The compounded bituminous networks satisfied the requirements of standard specifications and can be suitably used for waterproofing purpose and sealing of concrete joints. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 217–226, 2006     

Kinetics of low-temperature steam reforming of propane in a methane excess on a Ni-based catalyst

Systematic studies were performed on low-temperature steam conversion or low-temperature steam reforming (LTSR) of propane in an excess of methane on a Ni-based catalyst. The LTSR of the methane–propane mixture is a two-stage process involving the irreversible steam conversion of propane into carbon dioxide and hydrogen and reversible methanation of carbon dioxide. Above ~250°C, the methanation of carbon dioxide is quasi-equilibrium. The rate of propane conversion during the LTSR of the methane–propane mixture is first-order based on propane; its activation energy is ~120 kJ/mol and is almost independent of the methane, carbon dioxide, hydrogen, and steam concentrations. This very simple macrokinetic scheme allows us to correctly describe the experimental data and predict the temperature and flow rate of the mixture at which complete conversion of propane is achieved.     

Catalytic hydrocracking of bitumen at mild experimental condition

Mo-containing catalysts were prepared by impregnation method using silica-based porous supports and their physical properties were characterized by BET, XRD and TEM. Catalytic hydrocracking of bitumen extracted from oil sand was carried out in a high pressure reactor using Athabasca oil sand over 5 wt% Mo containing catalyst supported on SiO₂, MCF(Meso Cellular Foam) and SBA-15, respectively, under the conditions of 200 °C, 20 h and 10 atm of H₂ gas. Catalytic hydrocracking activity was estimated by analyzing H/C mole ratio based on EA data, and TGA was employed to compare the thermal behavior of bitumen before and after reaction. Upon hydrocracking over Mo/MCF catalyst, H/C was increased from 1.50 (bitumen itself) to 1.66.     

A novel approach for anionic bulk polymerization of 1,3,5‐tris(trifluoropropylmethyl)cyclotrisiloxane

Present work gave a new method for preparing polymethyl(3,3,3‐trifluoropropyl)siloxane (PMTFPS) in the mixing chamber of a torque rheometer using sodium silanolate as initiator, and ethyl acetate (EA) and dimethyl sulfoxide (DMSO) as promoters. The promoting effect of EA in the anionic bulk polymerization of 1,3,5‐tris(trifluoropropylmethyl) cyclotrisiloxane (F₃) was investigated in comparison with DMSO, a common promoter. Results showed that EA exhibited an effective promoting effect as DMSO did. When the polymerization was carried out for 4.0 min at 120°C in the presence of 0.30 mol L^?1 EA, the maximum of number average molecular weight (M _n = 2.45 × 10⁵ g mol^?1) of PMTFPS was obtained with high yield (89.2 wt%). The back‐biting reactions during the polymerization were almost suppressed and less than 0.75 wt% cyclic by‐products were obtained by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) for EA promoter system. Investigations of differential scanning calorimetry and thermogravimetic analysis showed that PMTFPS could be used in a wide range of operational temperatures. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Interaction of nafion ionomers toward various solvents

Interactions of Nafion (Naf) ionomer with water, aqueous ethanol (EA), aqueous isopropyl alcohol (IPA), and aqueous ammonia were investigated by attenuated total reflectance (ATR)–infrared (IR) spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and computational modeling studies. Microstructural features by ATR–IR revealed the existence of hydrophilic interaction of Naf with all solvents. The Naf membranes formed hydrogen bonds with water, aqueous EA, and IPA. The incorporation of solvents on the Naf matrix impaired the crystallinity, which was highest in the case of IPA. Of all the microsolvated structures of Naf investigated, the formation of H₃O⁺ ions was evident; in addition, H₅O₂⁺ ions appeared in the alcohol–water mixture, and NH₄⁺ ions were observed in the water–ammonia mixture along with a direct ion pair with the SO₃^? group in Naf. Theoretical studies based on computational modeling disclosed that the interchain distance increased with enhanced interactions (hydrophobic interactions in particular), and this was in good agreement with the highest swelling ratio of the Naf membrane in aqueous IPA and EA solvents. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of activated carbon from oil sands coke

Several million tonnes of oil sands coke are generated each year in Alberta, Canada as a by-product of bitumen upgrading. Due to its high carbon content, oil sands coke can be a suitable precursor for the preparation of activated carbon. In this study, delayed and fluid oil sands coke were physically activated in a muffle furnace under select conditions of activation time (2–6 h), temperature (800–900 °C), steam rate (0.3–0.5 mL/min), and activation atmosphere (CO₂, CO₂ + steam, and N₂ + steam). The activated products were characterized using thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, nitrogen adsorption, iodine and methylene blue tests. An increase in activation time and temperature resulted in higher surface areas in both delayed and fluid coke due to an enhanced etching of pores. An increase in steam rate led to the production of the highest specific surface area (577 m²/g) and iodine number (670 mg/g) within delayed coke; whereas, a lower steam rate resulted in the production of the highest specific surface area (533 m²/g) and iodine number (530 mg/g) in activated fluid coke samples.     

High-efficiency separation of oil sands using ChCl-based deep eutectic solvents

Deep eutectic solvents (DESs) are a kind of potential lixiviant for extraction processing. Unlike conventional ionic liquids (ILs), DESs are relatively cheap and environmentally friendly. Herein, three different ChCl-based DESs, namely, choline chloride/urea, choline chloride/ethylene glycol, as well as choline chloride/propandioic acid, were synthesized and used to enhance bitumen recovery from oil sand by petroleum ether extraction. The results showed a multiphase system formed after mixing the components at ~25°C, consisting of sands and clays, a DES layer, and a petroleum ether layer containing the bitumen. These DESs were immiscible with bitumen or petroleum ether. Coupled with a density difference, a clear phase separation was presented between the bitumen–petroleum ether mixture and DES. The DES functioned as a separating agent, keeping the petroleum ether–bitumen mixture and spent sand apart from each other. The results showed that the bitumen recovery was increased by ~12% compared with that without the DESs. We deduced that the enhancement in the separation may result from the reduction of adhesion between bitumen and sand by the DESs. The ChCl-based DESs and petroleum ether could be readily recycled to reduce industrial costs. After 10 cycles, the bitumen recovery remained above 86%.     

Interfacial tension behavior of athabasca bitumen/aqueous surfactant systems

The spinning drop method was used to measure the interfacial tension of Athabasca bitumen in contact with an aqueous phase (D₂O); variables included temperature, salinity, alkalinity, surfactant type (TRS 10–80, Suntech 5, sodium dodecyl sulfate), surfactant concentration, isopropyl alcohol concentration, bitumen drop size and age of interface. In the absence of surfactant, the bitumen/aqueous interfacial tension decreased with increasing temperature and salinity. Bitumen drops contacting alkaline medium exhibited interfacial tension minima below a pOH of three. In the presence of surfactant, the interfacial tension behavior was often complex. The interfacial tension-concentration plot for Suntech 5 surfactant exhibited two CMC type discontinuities. Low interfacial tension (<0.01 mN m^?1) was observed only in the presence of added electrolyte. Interfacial tension values were sensitive to the age of surfactant preparation and volume ratio of the oleic-to-aqueous phases. The interfacial tension of the bitumen/brine-TRS 10–80 system increased upon addition of isopropyl alcohol. An increase in temperature required an increase in salinity to maintain a constant low interfacial tension. The experimental results are discussed in terms of changes in the structure of the amphiphile at the bitumen/aqueous interface.     

Study of lignite catalytic depolymerization products. Chemical reduction of asphaltenes and toluene extract

Chemical reduction of bitumen and asphaltenes derived from a Spanish lignite depolymerized with BF₃ in phenol has been achieved by lithium in ethylamine. The extent of the reduction has been evaluated by means of elemental analysis and ¹H NMR spectroscopy, and some structural features have been established for the reduced products. After eight hours of reaction, the aromatic hydrogen content showed a large decrease, which was greater for asphaltenes than for bitumen. Structural parameters indicated for the treated samples that a half of the aromatic nuclei have been hydrogenated. ¹H NMR and IR spectroscopic data show a similar behaviour of asphaltenes and bitumen in the reduction process.     

Ordered thiol-functionalized mesoporous silica with macrostructure by true liquid crystal templating route

Ordered thiol-functionalized mesoporous silica has successfully been synthesized via co-condensation of tetramethyl orthosilicate (TMOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) in lyotropic liquid crystalline phase of Brij 56 surfactact (C₁₆EO₁₀). In contrast to the common synthesis in micellar solution, true liquid crystal templating synthesis can easily fabricate organic-functionalized mesoporous silica with desirable macro-morphology and the loading amount of organic moieties can also be controlled well. The resultant materials were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), nitrogen sorption, polarized optical microscopy, Fourier transform infrared (FT-IR) spectra, differential scanning calorimetry and thermogravimetric analysis (DSC–TGA), and elemental analyses (EA). Direct evidence of the presence of chemically attached thiol groups was provided by FT-IR, DSC–TGA and EA. Adsorption measurement indicates that the materials are effective for the removal of heavy metal ions from aqueous solutions. The Hg²⁺ adsorption isotherm fits Langmuir behavior, but the Type-IV adsorption isotherm for Cd²⁺ was unexpectedly observed, which is probably attributed to significantly different Cd²⁺ affinity ability for the thiol groups on the external surface and those lining the framework pore channels of the nanoporous adsorbent.     

Preparation and properties of macromolecular complexes consisting of [2-(diethylamino)ethyl]dextran hydrochloride and potassium metaphosphate

In aqueous solution [2-(diethylamino)ethyl]dextran hydrochloride (EA) was reacted with potassium metaphosphate (MPK) to form a series of water-insoluble macromolecular complexes (MC) at different hydrogen-ion concentrations (EA–MPK system). EA was also reacted with MPK in the presence of CaCl₂ (EA–MPK–CaCl₂ system). The structure and properties of MC obtained were compared with each other; elemental analysis, IR spectroscopy, solubilities, thermogravimetric analysis, and scanning electron microscopy were used to characterize these complexes. The molecular structure and properties of each MC were dependent on the hydrogen-ion concentration and whether the Ca²⁺ ion coexisted. It was suggested that MC prepared at acidic pH were composed of a relatively loose network including a small quantity of MPK, whereas those prepared at neutral and alkaline pH were composed of a relatively tight network including a large quantity of MPK. This seemed to be due to changes in the degree of dissociation and the conformation of EA and MPK with the hydrogen-ion concentration. MC in the EA–MPK–CaCl₂ system were supposed to have a rather tightly bound network structure due to the Ca²⁺ ion as compared with those in the EA–MPK system. © 1993 John Wiley & Sons, Inc.     

Coal gasification by a mixture of air and carbon dioxide in the filtration combustion mode

This paper presents the results of a numerical and experimental study of gasification of carbonaceous materials in the filtration combustion mode using mixtures of air with CO₂ as an oxidizer. The results obtained are compared with the results on gasification of carbonaceous materials by a steam–air mixture. It is shown that the replacement of steam in the gaseous oxidizer by an equal volume CO₂ leads to a marked reduction in the combustion temperature. The maximum calorific values of the product gas in coal gasification by a mixture of air and CO₂ are close to the values obtained for steam–air gasification.     

Preparation and characterization of chars and activated carbons from Saskatchewan lignite

Saskatchewan lignite was used as a precursor to prepare carbonaceous adsorbents for use as SO₂ adsorbent from flue gases. The lignite was carbonized producing char in a fixed bed microreactor system at different temperatures from 350 to 550 ^°C in nitrogen atmosphere. The chars obtained at 475 ^°C for 120 min exhibited the highest micropore surface area (136 m²/g) and volume (0.062 cm³/g) and the smallest median pore diameter (∼ 0.7 nm). Carbon dioxide and steam were used as activating agents. Activation of char at optimum conditions of 650–675 ^°C for 15 min with carbon dioxide and steam resulted in a further increase in micropore surface area (220 and 186 m²/g for CO₂ and steam, respectively) and volume (0.090 and 0.085 cm³/g for CO₂ and steam, respectively). The yield of char was 64 wt.%, while the yields of activated carbon were 60 and 57 wt.% for CO₂ and steam activation, respectively; all based on the mass of original lignite.     

Application of lanthanide n.m.r. shift reagents for functional group studies of shale bitumen asphaltenes

Ytterbium (fod)₃ was used as a shift reagent in conjunction with solution ¹H n.m.r. studies of asphaltene isolated from Devonian shale bitumen. Upon addition of the reagent, bands attributed to protons on alkyl groups alpha to oxygen atoms were shifted and separated from that attributed to protons alpha to two aromatic systems. Similar experiments with Green River bitumen asphaltene did not show any observable shift. The presence and absence of the ether formations in shale asphaltenes can be substantiated by ¹³C n.m.r.     

Steam fingering at the edge of a steam chamber in a heavy oil reservoir

The steam‐assisted gravity drainage (SAGD) process is one of the key in situ recovery processes being used today to recover heavy oil and bitumen. In this process, steam injected through a horizontal well, flows convectively towards the outer edges of a depletion chamber. At the edges of the depletion chamber, the steam releases its latent heat to the cool oil sand and raises its temperature. The heated oil is mobile and flows under the action of gravity to a horizontal production well located several metres below the injection well. It remains unclear what is the exact mechanism of chamber growth. Some have suggested that in addition to heat conduction, it is by convective steam flow in the form of pointed fingers at the edges of the chamber which penetrate the oil sand. In theory published by Butler [Butler, J. Can. Petroleum Technol. 1987;26(3):70–75], it was determined that the fingers can be as long as 6 m for Athabasca bitumen reservoirs. In this research, a new theory is derived and provides predictions of the rise rate which compare better to estimates derived from field thermocouple data and physical model experimental observations than values obtained from Butler's theory. The results suggest that in the absence of mobile water, heat conduction rather than steam fingers at the chamber edge is the dominant heat transfer mechanism.     

Testing of a Ni‐Al2O3 Catalyst for Methane Steam Reforming Using Different Reaction Systems

Ni‐Al₂O₃ catalyst activity was tested for methane steam reforming using two different reaction systems: a catalyst particle bed (0.42–0.5 mm catalyst particles diluted in SiC) with a surface area‐to‐volume ratio SA/V of 910 m^–1 and a porosity ? of 52 % and a catalyst‐coated metal monolith with an SA/V of 3300 m^–1 and an ? of 86 %. Under a steam‐to‐carbon ratio of 2.5 and at a temperature of 700 °C, the highest specific reaction rates were found for the catalyst‐coated monolith. The high SA/V and ?, together with the high rate of heat transfer of the metal monolith were found to be responsible of this optimum behavior. However, in both systems, the Ni‐Al₂O₃ catalyst suffered a catalyst deactivation during operation.     

Use of isocyanate production waste in the preparation of improved waterproofing bitumen

Waste residue generated during the production of toluene diisocyanate was used as a modifier in making improved waterproofing bitumen. The waste particles were surface‐modified with stearic acid. Various bitumen blends based on untreated particles, surface‐treated particles, and a combination of an SBS elastomer and waste particles were prepared. The optimized blends were subjected to evaluate their response against temperature and frequency sweeps. It was observed that improvement of the softening point and reduction in penetration could be correlated with the blend morphology in terms of the compatibility between the waste particles and the bitumen. The increased glass transition temperature and satisfactory phase miscibility in the modified bitumen observed in MDSC and DMA traces supported these findings. The coefficient of linear thermal expansion of the modified bitumen was found to be 1.21 × 10^?4/°C. The rheological studies revealed that time‐dependent properties of the modified bitumen were better in terms of its stiffness and elasticity than that of neat bitumen. The applicability of the Williams–Landel–Ferry (WLF) equation confirms the superior temperature‐dependent response of the modified systems over the control. It was noticed that stearate‐treated waste‐modified bitumen gives the best results in terms of a high complex modulus and a low phase angle. The newly formulated bituminous blend based on stearate‐treated waste meets the requirement of existing standard specifications for waterproofing felt. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1365–1377, 2003     

Thermoplastic elastomers based on recycled high‐density polyethylene,ethylene–propylene–diene monomer rubber,and ground tire rubber

High‐performance thermoplastic elastomers (TPEs), based on recycled high‐density polyethylene (HDPE^R), olefinic type ethylene–propylene–diene monomer rubber (EPDM), and ground tire rubber (GTR) treated with bitumen, were prepared by using dynamic vulcanization technology, and their structure–property relationships were investigated. It was established that special pretreatment of GTR by bitumen confers outstanding mechanical properties on the resulting TPEs. TPEs, containing GTR pretreated by bitumen, exhibit thermal behavior similar to that of the HDPE^R/EPDM basic blend in the temperature region up to about 340°C. Rheological measurements showed that bitumen acts as an effective plasticizer for the GTR‐containing TPEs. SEM, DSC, and DMTA results revealed improved adhesion between the particles of GTR treated by bitumen and the surrounding thermoplastic matrix, compared to that of the untreated GTR particles. It was concluded that bitumen acts as an effective devulcanizing agent in the GTR treatment stage. In the following steps of TPE production, bitumen acts simultaneously as a curing agent for the rubber components (EPDM/GTR) and as a compatibilizer for the blend components. GTR‐containing TPEs, prepared by extrusion technology, were reprocessed (by passing through the extruder six times) without any observable changes in their tensile properties, thermal stability, and melt viscosity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 659–671, 2005     

Rh–Fe/Ca–Al2O3: A Unique Catalyst for CO-Free Hydrogen Production in Low Temperature Ethanol Steam Reforming

Low temperature ethanol steam reforming (ESR) was studied over a series of 1 wt% Rh–x % Fe catalysts with various Fe loading (x = 0–10 wt%) and on different supports (Ca–Al₂O₃, SiO₂ and ZrO₂). The results show that close interaction between Rh and Fe is required to reduce the CO selectivity to almost negligible values. In addition, Rh–Fe supported on Ca–Al₂O₃ exhibits the best performance in terms of CO selectivity and hydrogen yield as compared to other supports. Characterization by XPS and XANES indicates the presence of Fe_xO_y species upon reduction, resulting in the formation of coordinatively unsaturated ferrous (CUF) active sites along the Rh–Fe_xO_y interface. These CUF sites promote water–gas shift reaction during low temperature ESR. Temperature programmed oxidation and Raman spectroscopy of spent catalysts also indicate that the addition of iron oxide reduces coke deposition and forms more reactive coke. Hence, the catalyst lifespan is significantly extended.     

Lycopene solubility in mixtures of carbon dioxide and ethyl acetate

In order to improve the efficiency of processes using supercritical (sc) carbon dioxide (CO₂) to micronize the carotenoid “lycopene”, it is important to know the solubility of lycopene in mixtures of the organic solvent ethyl acetate (EA) and the antisolvent CO₂ at elevated pressures. The solubility of lycopene has been determined for different temperatures (313–333 K), pressures (12–16 MPa) and CO₂ molar fractions (0.58–1). The obtained data show that CO₂ acts as an antisolvent in the system lycopene/EA/CO₂ in the range of CO₂/EA ratios studied. The solubility of lycopene is rather small with lycopene molar fractions ranging from 0.1 × 10⁻⁶ to 46 × 10⁻⁶. The solubility of lycopene increases with temperature, pressure and EA concentration.