Effect of hydrocarbon fractions, N₂ and CO₂ in feed gas on hydrogen production using sorption enhanced steam reforming: Thermodynamic analysis

H₂ yield and purity from sorption enhanced steam reforming (SE-SR) are determined by temperature, S:C ratio in use, and feed gas composition in hydrocarbons, N₂ and CO₂. Gases with high hydrocarbons composition had the highest H₂ yield and purity. The magnitude of sorption enhancement effects compared to conventional steam reforming (C-SR), i.e. increases in H₂ yield and purity, and drop in CH₄ yield were remarkably insensitive to alkane (C1-C3) and CO₂ content (0.1-10 vol%), with only N₂ content (0.4-70 vol%) having a minor effect. Although the presence of inert (N₂) decreases the partial pressure of the reactants which is beneficial in steam reforming, high inert contents increase the energetic cost of operating the reforming plants. The aim of the study is to investigate and demonstrate the effect of actual shale gas composition in the SE-SR process, with varied hydrocarbon fractions, CO₂ and N₂ in the feedstock

Chemical equilibrium analysis of hydrogen production from shale gas using sorption enhanced chemical looping steam reforming

Detailed chemical equilibrium analysis based on minimisation of Gibbs Energy is conducted to illustrate the benefits of integrating sorption enhancement (SE) and chemical looping (CL) together with the conventional catalytic steam reforming (C-SR) process for hydrogen production from a typical shale gas feedstock. CaO(S) was chosen as the CO2 sorbent and Ni/NiO is the oxygen transfer material (OTM) doubling as steam reforming catalyst. Up to 49 % and 52 % rise in H2 yield and purity respectively were achieved with SE-CLSR with a lower enthalpy change compared to C-SR at S:C 3 and 800 K. A minimum energy of 159 kJ was required to produce 1 mole of H2 at S:C 3 and 800 K in C-SR process, this significantly dropped to 34 kJ/mol of produced H2 in the CaO(S) /NiO system at same operating condition without regeneration of the sorbent, when the energy of regenerating the sorbent at 1170 K was included, the enthalpy rose to 92 kJ/mol H2, i.e., significantly lower than the Ca-free system. The presence of inert bed materials in the reactor bed such as catalyst support or degraded CO2 sorbent introduced a very substantial heating burden to bring these materials from reforming temperature to sorbent regeneration temperature or to Ni oxidation temperature. The choice of S:C ratio in conditions of excess steam represents a compromise between the higher H2 yield and purity and lower risk of coking, balanced by the increased enthalpy cost of raising excess steam

Steam reforming of shale gas in a packed bed reactor with and without chemical looping using nickel based oxygen carrier

The catalytic steam reforming of shale gas was examined over NiO on Al₂O₃ and NiO on CaO/Al₂O₃ in the double role of catalysts and oxygen carrier (OC) when operating in chemical looping in a packed bed reactor at 1 bar pressure and S:C 3. The effects of gas hourly space velocity GHSV (h⁻¹), reforming temperatures (600–750 °C) and catalyst type on conventional steam reforming (C-SR) was first evaluated. The feasibility of chemical looping steam reforming (CL-SR) of shale gas at 750 °C with NiO on CaO/Al₂O₃ was then assessed and demonstrated a significant deterioration after about 9 successive reduction-oxidation cycles. But, fuel conversion was high over 80% approximately prior to deterioration of the catalyst/OC, that can be strongly attributed to the high operating temperature in favour of the steam reforming process

Steam reforming of shale gas with nickel and calcium looping

High purity H₂ production from shale gas using sorption enhanced chemical looping steam reforming (SE-CLSR) was investigated at 1 bar, GHSV 0.498 h⁻¹, feed molar steam to carbon ratio of 3 and 650 °C for 20 reduction-oxidation-calcination cycles using CaO and 18 wt% NiO on Al₂O₃ as sorbent and catalyst/oxygen carrier (OC) respectively. The shale gas feedstock was able to cyclically reduce the oxygen carrier and subsequently reform with high H₂ yield and purity. For example H₂ yield of 31 wt% of fuel feed and purity of 92% were obtained in the 4th cycle during the pre-breakthrough period (prior to cycles with low sorbent capacity). This was equivalent to 80 and 43% enhancement compared to the conventional steam reforming process respectively

Effect of intermittent feeding and oat hulls to improve phytase efficacy and digestive function in broiler chickens

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The effect of a combined choline salicylate and cetalkonium chloride gel on particular strains of Pseudomonas aeruginosa, Staphylococcus spp. and Streptococcus spp.

The ongoing control of virulent bacteria strains is a challenge for today’s medicine. An example of this, is one widely used drug employed in treating less serious external oral and ocular bacterial infections. This is a gel containing both cetalkonium chloride and choline salicylate. However, whether in the era of expanding bacterial resistance this gel is still effective, is not clear. Hence, in our work, its antibacterial effect was studied against 13 strains of Pseudomonas aeruginosa, 6 strains of Staphylococcus spp. and 6 strains of Streptococcus spp. drawn from the collection of the Department of Microbiology, Virology and Immunology, Kazakh National Medical University, as well as against 30 strains of Staphylococcus spp. recently isolated from Kazakh medical students. This work demonstrated that Pseudomonas aeruginosa was insensitive to this preparation in all samples, while the sensitivity of Staphylococcus spp. and Streptococcus spp. was almost halved, compared to untreated samples. An interesting discovery was the greater resistance of strains obtained from student volunteers than from the collection. However, despite the evident resistance of some strains to the combined cetalkonium chloride and choline salicylate gel, we put forward that it can still be used in less serious external bacterial infections

Late Pleistocene slip rate of the Hoh Serh-Tsagaan Salaa fault system, Mongolian Altai and intracontinental deformation in central Asia

The Mongolian Altai is an intracontinental oblique contractional orogen related to the far-field effects of the Indo-Asian collision. Global Positioning System (GPS) data suggest that ~10-15 per cent of total Indo-Asia convergence is accommodated across this orogen. The Höh Serh-Tsagaan Salaa fault system is one of several NNW-SSE-trending oblique contractional faults acting to partition strain and accommodate shortening and dextral shear in the Mongolian Altai. This fault zone displaces late Pleistocene alluvium along the southwest piedmont of the Höh Serh range in western Mongolia. Along the central third of the fault zone, strain is partitioned onto two separate strands, one that accommodates nearly pure dextral shear and one that accommodates thrust motion. We determined late Pleistocene rates of deformation along each of the Höh Serh-Tsagaan Salaa fault strands based on differential GPS surveys and cosmogenic nuclide 10Be geochronology. Combining the measured offsets and 10Be dates yields a minimum right-lateral slip rate of 0.9 +0.2/-0.1 mm a-1; the minimum shortening rate is 0.3 ± 0.1 mm a-1, with uplift of at least 0.1 ± 0.1 mm a-1. Resolving the shortening and dextral components of deformation yields a slip vector of 0.8 +0.2/-0.1 mm a-1 toward 336°. This long-term deformation vector is consistent with the short-term strain field determined by GPS in the region and indicates that ~20 per cent of Indo-Asian deformation in the Mongolian Altai (~2 per cent of the total Indo-Asia strain accumulation) occurs along the Höh Serh-Tsagaan Salaa fault zone. Although rate data for other active faults in the Mongolian Altai are sparse, our results suggest that strain may be accommodated almost exclusively on discrete structures in this intraplate tectonic setting. © 2010 The Authors Geophysical Journal International © 2010 RAS