Performance of Na2O promoted alumina as CO2 chemisorbent in sorption-enhanced reaction process for simultaneous production of fuel-cell grade H2 and compressed CO2 from synthesis gas

The performance of a novel thermal swing sorption-enhanced reaction (TSSER) concept for simultaneous production of fuel-cell grade hydrogen and compressed carbon dioxide as a by-product from a synthesis gas feed is simulated using Na₂O promoted alumina as a CO₂ chemisorbent in the process. The process simultaneously carries out the water gas shift (WGS) reaction and removal of CO₂ from the reaction zone by chemisorption in a single unit. Periodic regeneration of the chemisorbent is achieved by using the principles of thermal swing adsorption employing super-heated steam purge.     

Stepwise Formation of Some Bivalent Metal Chelates with Sodium Alizarin Sulphonate

The stepwise protonation constants of the ligand and the stability constants of Alizarin Red S with some bivalent metal ions, Pb²⁺, Cu²⁺, Zn²⁺, and Hg²⁺ have been determined at 30° and at various ionic strengths viz. 0.02, 0.05, 0.15 and 0.20, maintained by sodium perchlorate solution. The formation of the chelate is evident from the shift between the (i) ligand and (ii) ligand and metal titration curves. From the values of the stepwise protonation constants and metal ligand stability constants at various ionic strengths, thermodynamic formation constants were evaluated by extrapolation to zero ionic strength. The order of stability constants was found to be: Cu > Pb > Zn > Hg     

Impossible pair constrained test path generation in a program

We have described an algorithm for generating the impossible pair (IP) constrained path in a program, if any. The complexity of the algorithm is polynomial in the number of vertices and the number of IP constrained paths actually existing in the program when the program digraph is acyclic, and it is a decreasing function of the number of impossible pairs.     

Selection of CO2 chemisorbent for fuel-cell grade H2 production by sorption-enhanced water gas shift reaction

New experimental data are reported to demonstrate that high purity H₂ can be directly produced by sorption-enhanced water gas shift (WGS) reaction using synthesis gas (CO + H₂O) as sorber-reactor feed gas. An admixture of a commercial WGS catalyst and a proprietary CO₂ chemisorbent (K₂CO₃ promoted hydrotalcite or Na₂O promoted alumina) was used in the sorber-reactor for removal of CO₂, the WGS reaction by-product, from the reaction zone. The promoted alumina was found to be a superior CO₂ chemisorbent for this application because (a) it could directly produce a fuel-cell grade H₂ product (<10–20 ppm CO) at reaction temperatures of 200 and 400 °C, and (b) it produced ∼45.6% more high purity H₂ product per unit amount of sorbent than the promoted hydrotalcite at 400 °C. Furthermore, the specific fuel-cell grade H₂ productivity by the promoted alumina at a reaction temperature of 200 °C was ∼3.6 times larger than that at 400 °C. These striking differences in the performance of the two CO₂ chemisorbents were caused by the differences in their CO₂ sorption equilibria and kinetics.     

Heat of Adsorption

Separation of gas mixtures by pressure swing and thermal swing adsorption processes is an established unit operation in the chemical industry. Mathematical simulations of these processes require precise knowledge of multicomponent gas adsorption equilibria, kinetics, and heats for the system of interest over all conditions of pressure, temperature, gas composition and adsorbate loading encountered by the adsorber during the separation process. Unfortunately, the published data on heats of adsorption are often not adequate. Limited heat data are generally available for pure gas adsorption, heat data for binary gas mixtures are rare, and heat data for mixtures containing three or more components are nonexistent.     

Development of an Online Heat Index Measurement System for Thermal Comfort Determination

This paper presents the development of a reliable heat index (HI) measurement system for evaluating the thermal comfort of a particular building or a particular area. The HI is an index that combines air temperature and relative humidity (RH) to determine the human-perceived equivalent temperature. To measure the air temperature and RH, temperature to digital converter and RH to voltage converter is used. HI is calculated online with the help of embedded firmware of the microcontroller. This calculated value is then transferred to the computer through standard RS 232 serial port. The same sensor node is tested with the RS 485 network standard by changing the transceiver of the node. The system is calibrated using four standard saturated binary salt solutions.     

Novel thermo‐responsive semi‐interpenetrating network microspheres of gellan gum‐poly(N‐isopropylacrylamide) for controlled release of atenolol

Thermoresponsive microspheres of gellan gum‐poly(N‐isopropylacrylamide), i.e., GG‐P(NIPAAm) semi‐interpenetrating polymer networks (semi‐IPNs) have been prepared by ionic crosslinking and used to study the controlled release (CR) of atenolol (ATL), an antihypertensive drug. Interaction of the drug with polymers was studied by Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) was used to confirm the polymorphism and molecular level dispersion of ATL. Scanning electron microscopy (SEM) indicated spherical nature and smooth surfaces of the microspheres with some debris attached on their surfaces. Mean particle size measured by laser light diffraction ranged between 34 and 76 μm. Equilibrium swelling performed at 25°C and 37°C in pH 7.4 phosphate buffer exhibited thermoresponsive nature of the polymers. In vitro drug release performed at 25°C and 37°C indicated temperature‐dependency of ATL release, which was extended up to 12 h. In vitro release profiles at both the temperatures confirmed thermoresponsive nature of the polymers giving pulsatile trends. The % cumulative release data have been fitted to an empirical equation to estimate transport parameters and to understand the nature of drug release. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Induced doping by sodium ion in poly(m-aminophenol) through the functional groups

Poly(m-aminophenol) (PmAP) was synthesized by the oxidative polymerization of m-aminophenol in sodium hydroxide medium using ammonium persulfate oxidant at room temperature. The synthesized polymer showed very good solution processability as it was well soluble in aqueous sodium hydroxide, dimethylsulfoxide (DMSO), dymethylformamide (DMF), etc. A free-standing film was cast from thermal evaporation of DMSO solution of the synthesized PmAP. The film was then doped with aqueous sodium hydroxide and methanol mixture by solution doping technique at room temperature. The doping conditions were standardized in terms of the DC-conductivity of the doped film. The doped PmAP was characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, Electron dispersion spectroscopy, X-ray diffraction spectroscopy, elemental analysis by atomic absorption spectroscopy, thermogravimetric analysis and DC-electrical conductivity. The DC-electrical conductivity of PmAP film was increased to 2.34 × 10^?5 S/cm from <10^?12 S/cm due to sodium ion doping. From all the above characterizations it was confirmed that the sodium ions were not the reason for the conduction. The incorporated sodium cation in the polymer through free –OH groups of the polymer chain was induced the electron cloud of the polymer and so the polymer became conducting.     

High molecular weight polypropylene nanospheres: Synthesis and characterization

The high molecular weight (MW) polypropylene with average particle size of 60 nm was synthesized by controlled growth mechanism using Ziegler–Natta catalyst. The atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies showed that PP nanoparticles were spherical in shape. Structure and crystallinity were concomitantly studied through Fourier transform infrared spectroscopy and X‐ray diffraction, respectively. It shows nanospherical PP particles with more crystallinity (～ 75%) compared with macrosized PP (～ 59%). In addition, differential scanning calorimetry studies revealed the finite particle size effect on T_g and the scale dependence T_g followed a first order exponential trend. As particle size goes down to nano‐ scale from macrosize, continuous elevation of T_g's were observed from ?25 to ?11°C. This phenomenon was directed to configuration entropy of single spherical nanoparticles of PP. The mechanical properties and surface roughness were also evaluated through AFM. At last, the properties of nanosized PP were compared with micron and macrosized particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

A Mean Phi Model for Pressure Filtration of Fine and Colloidal Suspensions

A working model for engineering analysis of pressure filtration is presented. Based on the filtration characteristics of fine and colloidal suspensions, the process was divided into two stages. A time‐invariant spatially uniform volume fraction of solids approximation is invoked in the growing filter cake stage (stage 1). A time‐dependent spatially uniform volume fraction of solids assumption is made in the cake consolidation stage (stage 2). The two models, named collectively as Mean Phi (M‐P) model, have a common physical basis, seamless continuity between the stages and internal consistency. The M‐P model has only three parameters: terminal or equilibrium volume fraction of solids in the filter cake that is related to its compressive yield stress, critical volume fraction of solids, which joins stage 1 and stage 2, and a permeability factor, which is common to stages 1 and 2. The model is validated with a large number of colloidal suspensions filtered under highly diverse physical‐chemical process conditions. A Pareto profile is identified that relates the timescale of filtration and the extent of dewatering achieved, the two most important performance indices of the process.