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The role of ZrO2 as different components in Ni-based catalysts for CO2 reforming of methane (CRM) has been investigated. The 10 wt.% Ni supported catalysts were prepared with ZrO2 as a support using a co-impregnation method. As a promoter (1 wt.% ZrO2) and a coactive component (10 wt.% ZrO2), the catalysts with ZrO2 were synthesized using a co-impregnation method. To evaluate the effect of the interaction, the Ni catalyst with ZrO2 as a coactive component was prepared by a sequential impregnation method. The results revealed that the activity, the selectivity, and the anti-coking ability of the catalyst depend upon the ZrO2 content, the Ni-ZrO2 interaction, basicity, and oxygen mobility of each catalyst resulting in different Ni dispersion and oxygen transfer pathway from ZrO2 to Ni. According to the characterization and catalytic activation results, the Ni catalyst with low ZrO2 content (as a promoter) presented highest selectivity toward CO owning to the high number of weak and moderate basic sites that enhance the CO2 activation-dissociation. The lowest activity (CH4 conversion ≈ 40% and CO2 conversion ≈ 39%) with the relatively high quantity of total coke formation (the weight loss of the spent catalyst in TGA curve ≈ 22%) of the Ni catalyst with ZrO2 as a support is ascribed to the lowest Ni dispersion due to the poor Ni-ZrO2 interaction and less oxygen transfer from ZrO2 to the deposited carbon on the Ni surface. The effect of a poor Ni-ZrO2 interaction on the catalytic activity was deducted by decreasing ZrO2 content to 10 wt.% (as a coactive component) and 1 wt.% (as a promoter). Although Ni catalysts with 1 wt.% and 10 wt.% ZrO2 provided similar oxygen mobility, the lack of oxygen transfer to coke during CRM process on the Ni surface was still indicated by the growth of carbon filament when the catalyst was prepared by co-impregnation method. When the catalyst was prepared by a sequential impregnation, the intimate interaction of Ni and ZrO2 for oxygen transfer was successfully developed through a ZrO2-Al2O3 composite. The interaction in this catalyst enhanced the catalytic activity (CH4 conversion ≈ 54% and CO2 conversion ≈ 50%) and the oxygen transport for carbon oxidation (the weight loss of the spent catalyst in TGA curve ≈ 7%) for CRM process. The Ni supported catalysts with ZrO2 as a promoter prepared by co-impregnation and with ZrO2 as a coactive component prepared by a sequential impregnation were tested in combined steam and CO2 reforming of methane (CSCRM). The results revealed that the ZrO2 promoter provided a greater carbon resistance (coke = 1.213 mmol·g−1) with the subtraction of CH4 and CO2 activities (CH4 conversion ≈ 28% and CO2 conversion ≈ %) due to the loss of active sites to the H2O activation-dissociation. Thus, the H2O activation-dissociation was promoted more efficiently on the basic sites than on the vacancy sites in CSCRM.

Grand Canonical Monte Carlo simulation of methanol adsorption on a graphite model with two hydroxyl groups grafted on the surface has been carried out to investigate the effects of temperature in the range of 278–360 K. The spacing between the OH groups was chosen so that two hydrogen bonds could be formed with the first methanol molecule. In the Henry law region, the isosteric heat at zero loading is greater than the condensation heat. When the loading is increased, the isosteric heat at low temperatures decreases slightly and exhibits a shoulder, which is associated with the formation of a cluster of methanol molecules around one OH group. On further increase in loading, the adsorbate–adsorbate interactions decrease because methanol begins to adsorb on the other OH group, resulting in a sharp decrease in the isosteric heat to a minimum, at which point both OH groups are covered with methanol molecules. At higher temperatures the isosteric heat at zero loading decreases but remains higher than the condensation heat. The shoulder heat is progressively diminished with temperature because methanol molecules are distributed over the two OH groups, due to the entropic effects. Interestingly, the minimum heat still occurs when the functional groups are covered and is even more pronounced at high temperatures.

Biogas derived from anaerobic digestion of biological wastes has been extensively used for heating purposes and/or electricity generation. Presence of hydrogen sulfide (H2S) in biogas affects engine performance adversely, thus reducing H2S content is a valuable part in practical application before utilizing biogas. Adsorptive separation is very appealing due to being an economical and effective method including the use of iron oxide based adsorbents. Pelletization of iron oxide adsorbents has never been reported among the adsorbents described to date. Therefore, H2S capture in two iron oxides (ferric oxide (Fe2O3) and magnetite (Fe3O4)) was experimentally investigated to determine technical feasibility of shaping pellets based on active iron oxide sorbent in removing H2S from a simulated gas stream (0.35 vol.% H2S balanced in N2). Many factors affecting the behavior of gas adsorption such as gas in-flow rate, adsorption temperature, binder loadings and textural characteristics were considered. The pellet strengths were also undertaken using a bulk crushing strength analyzer. The results indicated that higher temperature favors the diffusion of H2S molecules from the surface into the bulk of iron oxides. The H2S-sorption capacity of Fe3O4 sorbent was higher than that of Fe2O3 sorbent corresponding with the different pore volume and surface area in each adsorbent. With the same active Fe3O4, the extruded pellet produced with starch binder showed the excellent H2S uptake and crushing resistance. The higher gas in-flow rate had positive impact to contacting efficiency and mass transfer of solid and gas phase. The adsorbed H2S gas can be readily desorbed from the pellets with the desorption temperature below 60°C and the H2S-sorption capacity was consistent over repeated cycles. The pellets can be reused several times for consecutive adsorption/desorption cycles, without loss of performance in a large-scale reactor and therefore represent serious candidates for use in commercial absorbers.

In this work, activated carbon (AC) was prepared from bamboo waste using heat treatment. The AC was then modified to be nitrogen- and oxygen-enriched ACs by integration with urea, air oxidation, and KOH activation. At 25 °C, the nitrogen-enriched sample showed the highest CO2 adsorption affinity (uptake in pore at low pressures) and capacity (uptake in pore at moderate pressures, i.e., 1 bar). Whereas even at 0 °C, it still gave the highest affinity, but its capacity was reduced to be slightly lower than other samples. Consequently, a Grand Canonical Monte Carlo simulation was performed to macroscopically and microscopically investigate the CO2 adsorption behavior occurring in the experiments. The graphitic slit pore, in the pore width range of 0.7–1.5 nm, without a surface functional group (SFG), with pyridine (N-6), and with hydroxyl (OH) functional groups were modeled. (1) Adsorption affinity: the active site of SFG is dominant where CO2 molecules have the strongest interaction with N-functional group for all studied temperatures. The simulated results are consistent with the experimental data. (2) Adsorption capacity: the effect of pore width is more relevant. A sample with a more effective pore size gives higher capacity. However, the effective pore widths oscillated with temperature. High capacity at a suitable pore width resulted from the balance between the energy of motion and the packing of adsorbed molecules in order to optimize the energy. The energy of motion is more distinctive at high temperature; whereas, the commensurate packing is essential at low temperature.

Adsorption of methanol on functionalized graphite at 298 K was studied using a grand canonical Monte Carlo simulation to investigate the effects of functional group (Fn) properties, such as concentration, type, and configuration, on their saturation. It was found that the initial methanol molecule was adsorbed on the strongest active site of the functional groups with multiple hydrogen bonds. The additional methanol molecules were then adsorbed on the weaker active sites until they became saturated. Once the Fns were saturated, the adsorption processes were followed by monolayer and multilayer processes, and they were no longer influenced by Fn properties when the loading increased. In this work, we determined the effects of surface chemistry properties on their saturation state by the following: (1) The difference in Fn concentration is insufficiently influenced on the value and trend of the isosteric heat along the loading; the only difference is that the higher concentration causes the isosteric heat to shift to higher loadings. (2) The Fn type and configuration are affected on both value and trend of the isosteric heat. Heat contributions (fluid–fluid, fluid–functional group, and fluid–graphene basal plane), snapshots, local densities, and orientation distributions are discussed in this work.

The effect of gallium-promoted copper-based catalysts has been investigated in connection with the characteristic of the active copper phase. CuO-ZnO-Ga2O3catalysts with different gallium loadings were prepared using oxalate co-precipitation method. The effects of gallium loading on the properties of catalysts were studied by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and temperature-programmed reduction (TPR). The dispersion and metal area of copper were also determined by dissociative nitrous (N2O) adsorption technique conducted on a metal dispersion analyzer (BELCAT). The TPR profiles showed that the presence of two different reduction regions in the CuO-ZnO catalysts can be attributed to the reduction of highly dispersed copper oxide species (reduced at 246 °C) and bulk-like CuO (reduced at above 390 °C). By contrast, the only low-temperature reduction peak was presented in the TPR profiles after the Ga2O3loading was higher than 4 wt%. With the same molar ratio (Cu/Zn = 2:1), the reducibility of CuO-ZnO-Ga2O3was found to be more facile than CuO-ZnO due to the lower copper oxide crystallite sizes of gallium-promoted catalysts. Higher Ga2O3loadings resulted in an increase in both copper dispersion and metal surface area of all the catalysts studied in good agreement with the reduction behaviors in the TPR profiles, although all the gallium-promoted catalysts were slightly different for the reducibility.

Ethanol, a renewable bio-based resource, is the oxygenation in ethanol-diesel blends, thereby providing the potential to reduce exhaust emissions in compression-ignition engines. However, a major drawback of ethanol-diesel blends is the limited solubility and much difference of viscosity between ethanol and diesel fuel. These limitations result in phase separation, lubricity and properties of blended fuel. Biodiesel, an amphiphile or a surface-active agent, is known as an additive to improve the lubricity of diesel fuel. Therefore, this research is focused on the use of biodiesel as an additive for stabilizing the solubility of ethanol-diesel blends. A comparative study of phase stability of diesel-biodiesel-ethanol blends and an evaluation of some properties such as density, viscosity, pour point and heating value of different concentrations of the blends was carried out. The lubricity of the blended fuels was also investigated by the High Frequency Reciprocating Rig (HFRR). The result showed that the presence of biodiesel can improve fuel instability of the blends at room temperature for three months. Biodiesel, added in the ethanol-diesel blended fuels can improved the lubricity of blends as compared to diesel fuel. An increased amount of ethanol in blends can reduce the wear scar values of a test specimen. In contrast to heating value, density and viscosity at 40 oC of blends increase with increasing the amount of biodiesel.

A non-symmetrical aluminium complex containing a single metal centre has been synthesised and used\ud as a catalyst in the cycloaddition reaction of carbon dioxide to styrene oxide to yield a cyclic carbonate.\ud The reaction proceeds to around 70% conversion using the catalyst alone; however, it can be increased\ud to 90% conversion with the addition of tetrabutylammonium bromide (TBAB) as a co-catalyst. Interestingly,\ud the reaction proceeds as well with the organo-catalyst TBAB alone as it does with the aluminium catalyst\ud alone. This offers the potential for reduced cost processing and scale-up of the reaction through elimination\ud of the aluminium catalyst due to reduced catalyst costs and ease of separation of TBAB as a salt from the\ud reaction mixture. The rate constants for the aluminium catalysed reactions were determined as a function of\ud process temperature in the range 80–150 °C, as well as the activation energies for the reactions determined\ud from the Arrhenius plots. The activation energy for the aluminium catalyst alone was determined to be\ud 34 kJ mol−1, while adding TBAB as a co-catalyst reduced the activation energy by 11 kJ mol−1.

The adsorption of carbon dioxide on hydrotalcite-like compounds was investigated. Two different powdered hydrotalcites were used containing the cations nickel and iron. The powdered materials were screened for carbon dioxide adsorption using a thermogravimetric method and it was found that NiMgAl (Sample 1) hydrotalcite has the largest capacity for CO2, adsorbing 1.58 mmol g−1 at 20 °C, and highest rate of adsorption of up to 0.17 mmol g−1 min−1. This represented an increase of 53% in adsorption capacity, compared with NiMgAlFe (Sample 2). In order to improve the rheological behaviour of hydrotalcite paste for extrusion, hydrotalcite powders were combined with boehmite alumina (70:30 and 50:50 ratios of hydrotalcite:boehmite) before extrusion into pellets suitable for use in a fixed bed adsorber. These pellets were then re-crushed and further tested by thermogravimetric methods. The effects of temperature, composition and pre-treatment of the hydrotalcites on the adsorption of carbon dioxide and nitrogen are reported. At 20 °C, the amount of carbon dioxide adsorbed was between 2.0 and 2.5 mmol g−1 for all the hydrotalcite/alumina samples in this study, although this decayed rapidly with increasing temperature. The results are compared with silica gel as a common sorbent reference, and with literature values. Hydrotalcite/alumina samples have thermal stability and a high adsorption capacity for carbon dioxide over a wide range of temperatures. The composition of the hydrotalcite/alumina pellets investigated in this study has less effect upon the adsorption behaviour compared with the non-calcined hydrotalcite powder, thus allowing a wide choice of pellet compositions to be used.

Carbon dioxide (CO2) absorption in several imidazolium-based ionic liquids (ILs), pyridinium-based ionic liquids and a tetraalkylammonium-based poly(ionic liquid) (PIL), poly[(p-vinylbenzyl) trimethylammonium hexafluorophosphate] P[[VBTMA][PF6], was studied. The trend of CO2 solubility in all of the ILs increases dramatically with decreasing absorption temperature. Based on the same bis(triflamide) [Tf2N] anion, imidazolium, pyridinium and trihexyltetradecylphosphonium-based ionic liquids all show relatively similar CO2 solubilities, which were higher than for the [ES] anion. The highest CO2 absorption was found in a poly(ionic liquid) P[[VBTMA][PF6]], however, the monomer also showed higher CO2 capacity than the other ionic liquids. The poly(ionic liquid) is remarkable in that it can adsorb 77% of its body weight of CO2 with a selectivity over nitrogen of 70 : 1. The absorbed CO2 gas can be readily desorbed from ionic liquids and poly(ionic liquid) and the selectivity for CO2 over N2 was consistent over repeated cycles. The materials can be reused several times for consecutive sorption/desorption cycles, without loss of performance in a large-scale reactor and therefore represent serious candidates for use in commercial adsorbers.

The vapour pressures of several ionic liquids, liquid polymers and derivatives of glycerol were investigated by thermogravimetric analysis (TGA). The experimental method is described and discussed. Vapour pressure data for various solvents with low vapour pressures are reported at 100–120 °C. The thermogravimetric method for vapour pressure measurement is useful for the rapid screening of solvents. Ionic liquids have a low but detectable vapour pressure at 100–120 °C. The vapour pressures of liquid polymers such as poly(ethylenimine) and polyethylene glycols are in the same range, which might make these substances a less expensive alternative to ionic liquids.