Experimental investigation on the effect of natural gas composition on performance of autothermal reforming

This paper presents experimental study on catalytic autothermal reforming (ATR) of natural gas (NG) for hydrogen (_H2${\mathrm{H}}_2$) production over sulfide nickel catalyst supported on gamma alumina. The experiments are conducted on a cylindrical reactor of 30 mm in diameter and 200 mm in length with “simulated” NG of different composition under thermal-neutral conditions and fed with different molar air to fuel ratio (A/F$A/F$) and molar water to fuel ratio (W/F)$(W/F)$. The results showed that reforming performance is significantly dependent on A/F$A/F$, W/F$W/F$ and concentration of _C2+${\mathrm{C}}_{2+}$ hydrocarbons in inlet fuel. Fuels containing higher _C2+${\mathrm{C}}_{2+}$ hydrocarbons concentration have optimum performance in terms of more _H2${\mathrm{H}}_2$ at higher A/F$A/F$ and W/F$W/F$ but lower conversion efficiency. Good performance for ATR of fuel containing 15%–20% _C2H6${\mathrm{C}}_2{\mathrm{H}}_6$ can be achieved at A/F=5–7$A/F=5–7$ and W/F=4–6$W/F=4–6$, much higher than that for optimum performance of ATR of methane (A/F=3,W/F=2–2.5$A/F=3,W/F=2–2.5$). _CO2${\mathrm{CO}}_2$ in the inlet fuel does not have significant effect on the reversed water–gas shift reaction. Its effect on reforming performance is mainly due to the dilution of inlet fuel and products.     

A new gaseous and combustible form of water

In this paper we present, apparently for the first time, various measurements on a mixture of hydrogen and oxygen called HHO gas produced via a new electrolyzer (international patents pending by Hydrogen Technologies Applications, Inc. of Clearwater, Florida), which mixture is distinctly different than the Brown and other known gases. The measurements herein reported suggest the existence in the HHO gas of stable clusters composed of H and O atoms, their dimers H–O, and their molecules _H2${\mathrm{H}}_2$, _O2${\mathrm{O}}_2$ and _H2O${\mathrm{H}}_2\mathrm{O}$ whose bond cannot entirely be of valence type. Numerous anomalous experimental measurements on the HHO gas are reported in this paper for the first time. To reach their preliminary, yet plausible interpretation, we introduce the working hypothesis that the clusters constituting the HHO gas constitute another realization of a recently discovered new chemical species called for certain technical reasons magnecules   as well as to distinguish them from the conventional “molecules” [Santilli RM. Foundations of hadronic chemistry with applications to new clean energies and fuels. Boston, Dordrecht, London: Kluwer Academic Publisher; 2001]. It is indicated that the creation of the gaseous and combustible HHO from distilled water at atmospheric temperature and pressure occurs via a process structurally different than evaporation or separation, thus suggesting the existence of a new form of water, apparently introduced in this paper for the first time, with the structure (H×H)$(\mathrm{H}\times \mathrm{H})$–O where “×$\times$” represents the new magnecular bond and “-$-$” the conventional molecular bond. The transition from the conventional H–O–H species to the new (H×H)$(\mathrm{H}\times \mathrm{H})$–O species is predicted by a change of the electric polarization of water caused by the electrolyzer. When H–O–H is liquid, the new species (H×H)$(\mathrm{H}\times \mathrm{H})$–O can only be gaseous, thus explaining the transition of state without evaporation or separation energy. Finally, the new species (H×H)$(\mathrm{H}\times \mathrm{H})$–O is predicted to be unstable and decay into H×H$\mathrm{H}\times \mathrm{H}$ and O, by permitting a plausible interpretation of the anomalous constituents of the HHO gas as well as its anomalous behavior. Samples of the new HHO gas are available at no cost for independent verifications, including guidelines for the detection of the new species.     

Exergy analysis and optimization of methanol generating hydrogen system for PEMFC

An exergy analysis of methanol autothermal generating hydrogen system for PEMFC is presented. The process combines a catalytic combustion heat exchanger (CCHE), using partial off-gases containing hydrogen as feedstock, with an auto-thermal reformer (ATR), two water gas shift (WGS) reactors and four preferential oxidation (PROX) reactors. Energy and exergy of system were calculated and analyzed. The results demonstrated that inner exergy losses resulted from the irreversible heat transfer and reaction were the dominant factors. The most important destruction of exergy within the system was found to occur in the reformer and the catalytic combustion heat exchanger. Their ratios of exergy loss accounted for 25.03% and 24.95%, respectively, of the whole system. Based on results of thermodynamic and exergetic analysis, the reformer was optimized. The optimal W/M$W/M$ (molar water to methanol) is around 1.5–2.0 and A/M$A/M$ (molar air to methanol) is around 1.5. Certain recommendations were posed. The conclusions could help to optimize methanol autothermal generating hydrogen system for PEMFC.     

Microstructures and electrochemical characteristics of the La0.75Mg0.25Ni2.5Mx (M=Ni, Co; x=0–1.0) hydrogen storage alloys

In order to investigate the influences of the stoichiometric ratios of B/A (A: gross A-site elements, B: gross B-site elements) and the substitution of Co for Ni on the structure and the electrochemical performances of the _AB2.5–3.5${\mathrm{AB}}_{2.5–3.5}$-type electrode alloys, the La–Mg–Ni–Co system _{La0.75Mg0.25Ni2.5Mx}${\mathrm{La}}_{0.75}{\mathrm{Mg}}_{0.25}{\mathrm{Ni}}_{2.5}{\mathrm{M}}_x$ (M=Ni$\mathrm{M}=\mathrm{Ni}$, Co; x=0$x=0$, 0.2, 0.4, 0.6, 0.8, 1.0) alloys were prepared by induction melting in a helium atmosphere. The structures and electrochemical performances of the alloys were systemically measured. The obtained results show that the structures and electrochemical performances of the alloys are closely relevant to the M content. All the alloys exhibit a multiphase structure, including _LaNi2${\mathrm{LaNi}}_2$, (La,Mg)_Ni3$(\mathrm{La},\mathrm{Mg}){\mathrm{Ni}}_3$ and _LaNi5${\mathrm{LaNi}}_5$ phases, and the major phase in the alloys changes from _LaNi2${\mathrm{LaNi}}_2$ to (La,Mg)_Ni3+_LaNi5$(\mathrm{La},\mathrm{Mg}){\mathrm{Ni}}_3+{\mathrm{LaNi}}_5$ with the variety of M content. The electrochemical performances of the alloys, involving the discharge capacity, the high rate discharge (HRD) ability, the activation capability and the discharge potential characteristics, significantly improve with increasing M content. When M content x$x$ increases from 0 to 1.0, the discharge capacity rises from 177.7 to 343.62  mAh/g for the alloy (M=Ni)$(\mathrm{M}=\mathrm{Ni})$, and from 177.7 to 388.7 mAh/g for the alloy (M=Co)$(\mathrm{M}=\mathrm{Co})$. The cycle stability of the alloy first mounts up then declines with growing M content. The substitution of Co for Ni significantly ameliorates the electrochemical performances. For a fixed M content (x=1.0)$(x=1.0)$, the substitution of Co for Ni enhances the discharge capacity from 343.62 to 388.7 mAh/g, and the capacity retention ratio (_S100)$(S_{100})$ after 100 charging–discharging cycles from 51.45% to 61.1%.     

Nanostructured hematite for photoelectrochemical generation of hydrogen

With the advent of nanotechnology there has been a resurge of interest in α$\alpha$-Fe₂O₃, as suitable candidate for photoelectrochemical (PEC) splitting of water to generate hydrogen. This paper describes the enhanced PEC behaviour of nanostructured α$\alpha$-Fe₂O₃ thin films modified by various techniques. Nanostructured thin film/pellets of α$\alpha$-Fe₂O₃ prepared by various techniques and various dopants were investigated for their photoelectrochemical response. Thin films prepared by spray pyrolysis having particle size of 20–30 nm exhibited better photoresponse as compared to the films prepared by sol–gel methods, which further improved on doping with Zn. These films were further modified by (i) depositing Zn dots on the surface of α$\alpha$-Fe₂O₃ films using thermal evaporation method and (ii) irradiating it with 170 MeV Au¹³⁺${\mathrm{Au}}^{13+}$ ions. When used as electrode in photoelectrochemical cell, a significant increase in the photoresponse of these modified films were observed, details of which are discussed.     

Hydrogen production by autothermal reforming of LPG for PEM fuel cell applications

Indirect partial oxidation, or oxidative steam reforming, tests of a bimetallic Pt–Ni catalyst supported on δ$\delta$-alumina were conducted in propane–n  -butane mixtures (LPG) used as feed. _H2${\mathrm{H}}_2$ production activity and _H2/CO${\mathrm{H}}_2/\mathrm{CO}$ selectivity were investigated in response to different S/C, C/_O2$\mathrm{C}/{\mathrm{O}}_2$ and W/F ratios. It was confirmed that higher steam content in the reactant stream increases both the activity and the _H2/CO${\mathrm{H}}_2/\mathrm{CO}$ selectivity of the process. Low residence times created a positive impact on catalyst activity not only for hydrogen but also for carbon monoxide production due to the increased amount of fresh hydrocarbon in the feed stream. Hence, the highest selectivity level was obtained at intermediate residence times. The response of the system to C/_O2$\mathrm{C}/{\mathrm{O}}_2$ ratio was found to depend on the available steam content due to the complex nature of IPOX. The Pt–Ni catalyst was very prone to catalyst deactivation at low S/C ratios accompanied by high C/_O2$\mathrm{C}/{\mathrm{O}}_2$ ratios, but this problem was not encountered at high S/C ratios. A comparison of catalyst performance for different propane-to-n-butane ratios in the LPG feed indicated that the Pt–Ni catalyst has slightly better activity and selectivity at higher n-butane contents at the expense of becoming more sensitive to coke deposition.     

Kinetic study on nonisothermal dehydrogenation of TiH2 powders

The nonisothermal dehydrogenation of TiH₂ powders was studied using thermogravimetry and differential scanning calorimetry. The reaction model was established by estimating the activation energy. The results show the nonisothermal dehydrogenation occurred in a four-step process. The hydrogen released from the TiH_1.5∼2$\text{Ti}{\mathrm{H}}_{1.5\sim 2}$ phase in the first step, which led to the decrease of activation energy. The second step was derived from the formation of βH${\beta }_H$ in δ$\delta$ phase and the reaction model was Phase boundary reaction. In the third step, the hydrogen started to release from the βH${\beta }_H$ phase, and then the βH→αH${\beta }_{\mathrm{H}}\to {\alpha }_{\mathrm{H}}$ phase transformation happened. So the activation energy Eα$E_{\alpha }$ underwent a decrease followed by a quick increase. The fourth step corresponded to the formation of αH${\alpha }_H$ in βH${\beta }_H$ phase, and the slight oxidation resulted in the small fluctuation of activation energy.     

CO2 reforming of CH4 by combination of thermal plasma and catalyst

Experiments on synthesis gas preparation from dry reforming of methane by carbon dioxide with thermal plasma only and cooperation of thermal plasma with commercial catalysts have been performed. In all experiments, nitrogen gas was used as the plasma gas to form a high-temperature jet injected into a tube reactor. A mixture of _CH4${\mathrm{CH}}_4$ and _CO2${\mathrm{CO}}_2$ was fed vertically into the jet. Both kinds of experiments were conducted in the same conditions, such as total flux of feed gases, the molar ratio of _CH4/_CO2${\mathrm{CH}}_4/{\mathrm{CO}}_2$, and the plasma power except with or without catalysts in the tube reactor. Higher conversion of _CH4${\mathrm{CH}}_4$ and _CO2${\mathrm{CO}}_2$, higher selectivity of _H2${\mathrm{H}}_2$ and CO, and higher specific energy of the process were achieved by thermal plasma with catalysts. For example, the conversions of _CH4${\mathrm{CH}}_4$ and _CO2${\mathrm{CO}}_2$ were high to 96.33% and 84.63%, and the selectivies of CO and _H2${\mathrm{H}}_2$ were also high to 91.99% and 74.23%, respectively. Both were 10–20%$10–20\%$ higher than those by thermal plasma only.     

A new electronic theory of pericyclic chemistry and aromaticity is proposed: The Cplex-isoelectronic theory. Consistent with Santilli's hadronic chemistry

A new electronic theory of pericyclic chemistry and aromaticity, in line with the Robinson/Ingold electronic theory, is proposed. It is referred to as the Cplex-isoelectronic theory. This represents the first successful theory that is not based on quantum mechanics. There are three assumptions in this theory (1) ADEP, (2) SDEP and (3) SDSE. The ADEP assumption refers to isoelectron pairs moving in an antiperiplanar mode in relation to the plane of the molecule. SDEP relates to isoelectron pairs moving in a synperiplanar mode and SDSE refers to single isoelectrons moving in a synperiplanar mode. These assumptions are deduced from nucleophilic, radical addition, _SN2$S_{\mathrm{N}}2$ and _SN2^′$S_{\mathrm{N}}{2}^{\prime }$ reactions and the anomeric effect. Application of the ADEP concept to pericyclic reactions is supported by Complexity theory and backed up by direct empirical evidence from 1,3-dipolar cycloaddition reactions involving nitronates and by its ability to predict the experimental data. The heavy atom effect provides experimental evidence for the SDSE mode in pericyclic reactions. The HOMO Diels–Alder is consistent with the SDEP concept. Evidence for the assumptions in aromatic compounds is found in the observation of a diamagnetic ring current in the presence of an applied field and in the applicability of the Biot–Savart law. The Cplex-isoelectronic theory makes different predictions from the present quantum chemical methods in some cases, namely the existence of suprafacial concerted thermal [2+2]$[2+2]$, [4+4]$[4+4]$, [6+2]$[6+2]$ and [6+6]$[6+6]$ cycloadditions, suprafacial concerted photochemical [4+2]$[4+2]$ and [6+4]$[6+4]$ cycloadditions, stepwise [2+2+2]$[2+2+2]$ cycloadditions of ethyne, diamagnetic ring currents for some cyclic systems with 4nπ$4n\pi$ electrons. The available empirical evidence is consistent with these predictions. This finding is consistent with Santilli's hadronic chemistry which proposes that the present quantum chemical theories require the addition of a small correction factor for molecules with two or more electrons.     

Second law analysis of forced convection in a circular duct for non-Newtonian fluids

The second law characteristics of fluid flow and heat transfer inside a circular duct under fully developed forced convection for non-Newtonian fluids are presented. Heat flux is kept constant at the duct wall. Analytical expressions for dimensionless entropy generation number (_NS$N_{\mathrm{S}}$), irreversibility distribution ratio (Φ  ), and Bejan number (Be$\mathit{Be}$) are obtained as functions of dimensionless radius (R$R$), Peclet number (Pe$\mathit{Pe}$), modified Eckert number (Ec$\mathit{Ec}$), Prandtl number (Pr), dimensionless temperature difference (Ω  ), and fluid index (m$m$ or n$n$). Spatial distributions of local and average entropy generation number, irreversibility ratio, and Bejan number are presented graphically. For a particular value of fluid index, n=1$n=1$ (or m=2$m=2$), the general entropy generation number expression for a non-Newtonian power-law fluid reduces to the expression for Newtonian fluid as expected. Furthermore, entropy generation minimization is applied to calculate an optimum fluid index (_nEGM$n_{\mathrm{EGM}}$). A correlation is proposed that calculates _nEGM$n_{\mathrm{EGM}}$as a function of group parameter (Ec×Pr/Ω$\mathit{Ec}\times \mathit{Pr}/\Omega$) and Peclet number (Pe$\mathit{Pe}$) within ±5% accuracy. Finally, for some selected fluid indices, the governing equations are solved numerically in order to obtain Nusselt number. It is observed that the numerically obtained asymptotic Nusselt number shows excellent agreement with the analytically obtained Nusselt number.     

Hydrogen storage and induced properties in non-metallic catalytic materials

Particular active sites, ^xM${}^x\mathrm{M}$–^yM^′${}^y{\mathrm{M}}^{\prime }$ (where x$x$ and y$y$ are the number of unsaturations, i.e. anionic vacancies, on each cation M and M^′${\mathrm{M}}^{\prime }$) involving reactive hydrogen are created during the activation of non-metallic catalytic materials. The anionic vacancies created in bulk and at the surface of the solid, by the loss of _H2O${\mathrm{H}}_2\mathrm{O}$ or _H2S${\mathrm{H}}_2\mathrm{S}$, are able to receive hydrogen in a hydridic form according to a heterolytic dissociation (X^2-Mⁿ⁺□+_H2→XH^-Mⁿ⁺H^-${\mathrm{X}}^{2-}{\mathrm{M}}^{n+}\square +{\mathrm{H}}_2\to {\mathrm{XH}}^{-}{\mathrm{M}}^{n+}{\mathrm{H}}^{-}$ with X=O$\mathrm{X}=\mathrm{O}$ or S). The non-metallic catalytic materials become catalytic hydrogen reservoirs. Besides a high reactivity, the hydrogen species, stored in the solid, present marked diffusion properties leading to a dynamic behavior of the solid and active sites.     

Evaluation of conversion efficiency of light to hydrogen energy by Anabaena variabilis

Cyanobacteria provide an efficient system for producing _H2${\mathrm{H}}_2$ from water using solar energy. The energy conversion efficiency can be defined by the ratio of _H2${\mathrm{H}}_2$ produced to the light energy absorbed. An IR and opalescent plate method was used to measure the light energy absorbed. Since cyanobacteria absorb light in the visible range but not in the infrared range, the net amount of light energy absorbed by the cells can be estimated by measuring the IR and visible light intensities transmitted through the biochamber. A rectangular biochamber was used for measuring the conversion efficiency from light energy to _H2${\mathrm{H}}_2$ energy. A quantum meter and radiometer were used to measure the light intensity transmitted through the chamber. Anabaena variabilis was cultured in a BG11 medium with 3.6 mM NaNO₃${}_3$ and the light intensity was 40–50 μmol/m²/s$\mathrm{\mu }\mathrm{mol}/{\mathrm{m}}^2/\mathrm{s}$ in the growth phase and 120–140 μmol/m²/s$\mathrm{\mu }\mathrm{mol}/{\mathrm{m}}^2/\mathrm{s}$ in the _H2${\mathrm{H}}_2$ production phase. The maximum _H2${\mathrm{H}}_2$ production was 50 ml for 40 h and cell density was 1.2 g/l. The _H2${\mathrm{H}}_2$ production rate was 4.1 ml _H2/g${\mathrm{H}}_2/\mathrm{g}$ dry cell weight/h. Based on the light absorbed in the _H2${\mathrm{H}}_2$ production phase, the energy conversion efficiency from light to _H2${\mathrm{H}}_2$ was 1.5% on average and 3.9% at the maximum. Based on the light energy absorbed in the cell growth and _H2${\mathrm{H}}_2$ production phases, the energy conversion efficiency was 1.1% on average.