Basic Oxides Research Articles

Adaptable graphitic C6N6-based copper single-atom catalyst for intelligent biosensing

Self-adaptability is highly envisioned for artificial devices such as robots with chemical noses. For this goal, seeking catalysts with multiple and modulable reaction pathways is promising but generally hampered by inconsistent reaction conditions and negative internal interferences. Herein, we report an adaptable graphitic C6N6-based copper single-atom catalyst. It drives the basic oxidation of peroxidase substrates by a bound copper-oxo pathway, and undertakes a second gain reaction triggered by light via a free hydroxyl radical pathway. Such multiformity of reactive oxygen-related intermediates for the same oxidation reaction makes the reaction conditions capable to be the same. Moreover, the unique topological structure of CuSAC6N6 along with the specialized donor-π-acceptor linker promotes intramolecular charge separation and migration, thus inhibiting negative interferences of the above two reaction pathways. As a result, a sound basic activity and a superb gain of up to 3.6 times under household lights are observed, superior to that of the controls, including peroxidase-like catalysts, photocatalysts, or their mixtures. CuSAC6N6 is further applied to a glucose biosensor, which can intelligently switch sensitivity and linear detection range in vitro.

Conditions and Magmas Sources of Summit and Flank Eruptions of the Klyuchevskoy Volcano in 2020–2021: Isotope (Sr-Nd-Pb-O)-Geochemical Data

In 2021 a unique event occurred on Klyuchevskoy volcano (Kamchatka). After more than 30 years dominance of terminal eruptions a flank vent was formed. It was named after corresponding member of the Academy of Sciences USSR G.S. Gorshkov. The eruption began immediately after the end of the summit crater activation in 2020–2021 at an altitude of 2850 m in the northwestern part of the volcano, where no manifestations of flank volcanism were observed earlier. This paper presents geochemical and isotopic Sr-Nd-Pb-O data for lavas of the summit and flank eruptions of the Klyuchevskoy volcano in 2020–2021. A comparative petrographic analysis was carried out and the chemical composition of the Ol, Cpx, Pl phenocrysts of these lavas was analyzed. The lavas of both eruptions are alumina andesitic basalts of normal alkalinity. Variations of basic oxides in the lavas of the summit eruption and in the lavas of the G.S. Gorshkov vent are SiO2 53.1–53.2 wt. % and 51.6–53.2 wt. %, MgO 5.6 wt. % and 5.5–6.0 wt. %; respectively. Estimates of temperatures and pressures of plagioclase crystallization showed that for lavas of the summit eruption they were 1210–1118°С and 12.3–3.6 kbar, for lavas of the flank vent 1203–1119°С and 9.0–3.3 kbar. The content of the main elements, the proximity of the conditions of plagioclase generations, and the features of variations in the chemical composition of Ol, Cpx, and Pl phenocrysts in the lavas of both eruptions indicate the genetic relationship of the magmas that fed the summit and flank eruptions. The lavas of the summit eruptions of 2016, 2020–2021, as well as the lavas of the previous summit eruptions of the Klyuchevsky volcano, are characterized by highly sustained Sr-Nd-Pb isotopic characteristics: 87Sr/86Sr = 0.703625–0.703626, 143Nd/144Nd = 0.513085–0.513102, 206Pb/204Pb = 18.3148–18.3179). Isotopic ratios 207Pb/204Pb (15.5022–15.5107) and 208Pb/204Pb (37.9597–38.0143) are significantly higher for the lavas of the last summit and flank eruptions than for all Klyuchevskoy’s lavas of the past, which indicates more complex processes of magma evolution at crustal levels. The values of δ18O = 6.49–7.39 rel. units (SMOW) in the lavas of the considered eruptions are consistent with previously published data on the Klyuchevsky volcano. The lavas of the Gorshkov vent are enriched with Ba, Zr, Sr and other incompatible elements at constant values of MgO in comparison with the lavas of the last summit eruptions, which indicates differences in the ways of evolution of their magmas. Sharply increased values of the 87Sr/86Sr ratio (0.703673–0.703743) in the lavas of the G.S. Gorshkov vent, not previously observed in the lavas of the Klyuchevsky volcano, testifies to intensive assimilation of crustal matter by the initial melts in the northwestern part of the volcano.

Effects of sludge on the ash fusion behaviors of high ash-fusion-temperature coal and its ash viscosity predication

The co-gasification of sludge and coal is a promising way to regulate coal ash fusion characteristics and recover energy from sludge simultaneously. In this paper, the ash fusion behaviors of high ash-fusion-temperature (AFT) Datong coal, textile dyeing sludge (TDS), their mixtures, and the corresponding AFT modification mechanisms on laboratory scale were investigated by an AFT tester, X-ray diffractometer, Raman spectrometer, and FactSage software. The AFTs of Datong coal mixtures decreased slowly when TDS share was in the range of 0–6%, quickly (6–9%), and then nearly stable (>9%) because of its corresponding increasing basic oxide values (the total content of SO3, CaO, MgO, Fe2O3, Na2O, and K2O). The generations of low melting-point minerals of hercynite and anorthite with TDS additions resulted in the AFT decrease. The decreasing intensity of Si–O–Si peak and the increasing ratio bond of bridging oxygen and non-bridging oxygen led to the AFT decrease. Both the decreases in the temperature at which all minerals change into liquid-phase and the continuously increasing liquid-phase content (at the same relative high temperature) in Datong coal mixed ashes with increasing TDS mass ratio were contributed to the variations of AFT. The viscosity-temperature characteristics variation was also predicted using FactSage calculation. The 9.0–12.0% mass ratio of TDS might be suitable for Datong coal entrained-flow bed gasification.

A simple and sensitive method for the determination of methylene blue and its analogues in fish muscle using UPLC-MS/MS

A new, simple and sensitive method for determining and confirming methylene blue and its analogues such as azure A, azure B, azure C, thionine, and new methylene blue in fish muscles have been developed. The method is based on acetonitrile extraction followed by extract purification using dispersive solid-phase extraction (dSPE) with basic aluminium oxide (ALN) and solid-phase extraction (SPE) using primary and secondary amines (PSA) sorbent in matrix adsorption mode. The separation and detection of the dyes in the fish extract are achieved within 5 min by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) using an octadecyl analytical column with a mixture of acetonitrile, methanol and 0.1% formic acid as a mobile phase in gradient elution. The developed method has been in-house validated according to European law. The method recovery for fish muscle was 98.3–103.1%, whereas the decision limit (CCα) was from 0.45 to 0.49 µg kg−1.

Synthesis, Characterization and Studies of Nanosized BaSnO3 and Its Poly (vinylalcohol) Nanocomposite Film

Synthesis of nanosized materials integrates the materials synthetic technology. Nanosized bimetallic oxides constitute class materials in concerned with its applications. The present work reports the synthesis of barium stannate (BaSnO3)nanopowder by self-propagating combustion reaction using polyvinyl alcohol (PVA) as a fuel. Initially basic oxides barium oxide (BaO) and tin oxide (SnO2) are also prepared by combustion route. Further barium stannate-PVA nanocomposite (BaSnO3-PVA) is prepared by dispersion of BaSnO3 material into PVA matrix using solvent casting method. Structural characterization of oxide and nanocomposite was studied by X-ray diffraction (XRD) tool and bonding nature by Fourier transfer infrared study (FT-IR) respectively. Thermal behavior of both the sample is well studied by thermo gravimetric analysis (TGA). Electrochemical study of the sample is carried out by cyclic voltammetry (CV) instrumentation. Varied morphology and particle size of the sample was analysed through Transmission electron microscope (TEM) tool.

Regulation of ash slagging behavior of palm oil decanter cake by alum sludge addition

Combustion of palm oil decanter cake (PODC) is a propitious alternative waste to energy means. However, the mono-combustion of PODC prompt severe ash slagging behavior which give rise to reduction in heat transfer and also shorten the lifespan of combustion reactors. In this study, alum sludge (AS) was introduced at different proportion of 30%, 50% and 70% to revamp the slagging characteristics of PODC during combustion. The addition of AS improved ash fusion temperature of PODC during co-combustion as ash fusion temperature increased significantly under high AS dosage. Slagging and fouling indices showed that at 50% AS addition, slagging tendency of the co-combustion ashes can be ignored. The predictive model for PODC-AS combustion showed good correlation coefficient with 0.89. Overall, co-combustion of PODC and AS is an ideal ash related problem-solving route. The proposed PODC slagging preventive method by AS was based on: (1) limited amount of aluminum content in PODC-AS system resulted in development of refractory ash (2) reduction in proportion of basic oxide which act as ash bonding glue played important role in the regulation of slagging (3) reduction of cohesive bond by formation of spongy and porous structure which prevented ash slagging.

Surface Modifications of CuO Doped Carbonaceous Nanosorbents and their CO2 Sorption Properties

In this study, carbonized apricot stones and rice husk were utilized as feedstock for the synthesis of CuO-loaded carbonized sorbents for the removal of carbon dioxide (CO2) from gas mixtures. The specific surface area of carbonized sorbents increased with increasing carbonization temperature, resulting in a porous structure with enhanced sorption capacity. The presence of pores and the development of porosity in the sorbents were confirmed by SEM images. CuO nanoparticles were well-dispersed on the surface of carbonized sorbents, and the particle sizes were between 60‒100 nm. Chemical interactions between acidic carbon dioxide and basic copper oxide led to improved adsorption properties. The sorption characteristics of the carbonized sorbents were studied under dynamic conditions, and the results showed that CuO-loaded carbonized apricot stones and rice husk had the maximum sorption capacity for CO2, with efficiencies of 98% and 91%, respectively. These findings indicate that carbonized apricot stones and rice husk can be utilized as low-cost and eco-friendly feedstock for the production of efficient CO2 sorbents.

Synergistic effects and mechanism of the ternary flux system Fe2O3-CaO-MgO on the coal ash slag fluidity

Basic oxides are usually widespread in low-rank coals and cause many ash-related problems in gasification applications. In this paper, the synergistic effects of the ternary flux system of Fe2O3-CaO-MgO in lowering the ash fusion temperature and improving the viscosity-temperature characteristics were verified by testing the properties of samples with different Fe2O3/(CaO + MgO) ratios. The flow temperatures and temperatures of the critical viscosity decreased and then increased with the decrease of Fe2O3/(CaO + MgO) ratio and reached the lowest point when the iron oxide and alkaline earth metal oxide (CaO, MgO) contents were close to each other. From the perspective of mineral transformation, the formation of low melting point ferroan spinel and the eutectic between anorthite and ferroan spinel are the main mechanisms of synergism. No severe crystallization was observed in the iron-rich slags because Fe2+ could reduce the crystallization tendency. As CaO and MgO dominated the basic oxides, a CaO/MgO ratio of 4:6 effectively limited the crystallization and lower the temperature of critical viscosity (TCV). Thus, when regulating the coal ash fluidity, the content of iron oxide and the ratio between CaO and MgO should be consciously balanced to meet the requirements of the gasifier for slag removal.

Structural, textural, surface basic and catalytic properties of an aged Mg/Al layered double hydroxide and its calcination products

The influence of the length of an aging treatment on the structural and textural properties of a 2:1 Mg/Al layered double hydroxide (LDH) obtained by coprecipitation under low oversaturation conditions was examined. Increasing the aging time led to more crystalline solids consisting of increasingly large crystals; also, however, it reduced the number of macropores and decreased the specific surface area of the solids. Calcination of the LDH gave a basic mixed oxide [Mg(Al)O]. Extending the aging treatment increased the number of surface basic sites in the mixed oxide. All solids were characterized by using various instrumental techniques and used as catalysts in the Baeyer–Villiger reaction, where the calcined materials exhibited the best catalytic properties. Also, all catalysts were reusable with no appreciable loss of activity.

Electrochemical properties of Au Nanoparticles

TiO2 NPs powder (titanium oxide nanoparticles powder) is synthesized via anodization in 0.7 M HClO4 is annealed in N2 at 450°C for 3 hrs to obtain the TiO2 NPs -N2 powder as catalyst support to which Au is loaded via photodeposition technique using tetrachloroauric acid (HAuCl4) and isopropanol as a sacrificial donor. The physicochemical characterizations of TiO2 NPs arrays powder were performed by transmission electron microscopy (TEM). The TEM image suggested that Au nanoparticles were circular and there was a tendency of agglomerations. The electro-catalytic activity of Au NPs/TiO2-NTs-N2 catalysts in ferrocyanide system , KOH ,and H2SO4 electro-oxidation was examined by cyclic voltammetry (CV) and contrasted with a financially accessible polycrystalline gold electrode. Au-TiO2 NPs-N2 powder electrode catalyst displays a strikingly high electrocatalytic activity in KOH and H2SO4 solutions. The results indicate Au NPs/TiO2-NTs-N2 catalysts as a promising support material improve the excellent electro-catalytic activity for acidic and basic oxidation.

Effect of CO2/propane ratio and trimetallic oxide catalysts on maximizing dry reforming of propane

This study aimed at increasing the dry reforming reaction of propane with CO2 by using trimetallic oxide catalyst based on the reactive support of ZrO2/TiO2. Multiple basic (Mg, Be and Ba) and transition metal oxide (Cu, Fe) and Al were impregnated separately into 5%ZrO2/TiO2 catalyst support and characterized by XRD, BET, CO2-TPD and NH3-TPD. The catalysts showed an increase in the number of basic surface sites, with the trimetallic catalysts exhibiting more than 2.2–9.7 times the original number of basic sites of the Zr/Ti oxide support. In order to maximize greenhouse gas conversion, selected ratios of CO2/propane were correlated to increase syngas (CO and H2) product and promote more CO2 reactions via surface intermediates from CC bond dissociation of propane. Utilizing trimetallic catalysts enabled a three folds increase of CO yield compared to the reactive support used in the study. Although the selectivity towards H2 and CO increase with trimetallic catalysts, 2%Fe/5%ZrO2/TiO2 and 2%Be/5%ZrO2/TiO2 exhibited the highest propane dry reforming conversions (84–97%) with yields of H2 (35–51%) and CO (60–68%), respectively. The study demonstrated that each trimetallic oxide catalyst consumed CO2 differently, promoting distinct CC bond breaking patterns of propane over the catalyst surface.

Hydrogen spillover and substrate-support hydrogen bonding mediate hydrogenation of phenol catalyzed by palladium on reducible metal oxides.

Substrate-support interactions play an important role in the catalytic hydrogenation of phenolic compounds by ceria-supported palladium (Pd/CeO2). Here, we combine surface contrast solution NMR methods and reaction kinetic assays to investigate the role of substrate-support interactions in phenol (PhOH) hydrogenation catalyzed by titania-supported palladium (Pd/TiO2). We show that PhOH adsorbs on the catalyst via a weak hydrogen-bonding interaction between the -OH group of the substrate and one oxygen atom on the support. Interestingly, we observe that the addition of 20 mM inorganic phosphate results in a ∼2-fold destabilization of the PhOH-support interaction and a corresponding ∼2-fold inhibition of the catalytic reaction, suggesting an active role of the PhOH-TiO2 hydrogen bond in catalysis. A comparison of the data measured here with the results previously reported for a Pd/CeO2 catalyst indicates that the efficiency of the Pd-supported catalysts is correlated to the amount of PhOH hydrogen bonded to the metal oxide support. Since CeO2 and TiO2 have similar ability to uptake activated hydrogen from a noble metal site, these data suggest that hydrogen spillover is the main mechanism by which Pd-activated hydrogens are shuttled to the PhOH adsorbed on the surface of the support. Consistent with this hypothesis, Pd supported on a non-reducible metal oxide (silica) displays negligible hydrogenation activity. Therefore, we conclude that basic and reducible metal oxides are active supports for the efficient hydrogenation of phenolic compounds due to their ability to hydrogen bond to the substrate and mediate the addition of the activated hydrogens to the adsorbed aromatic ring.

Effect of Slightly Acidic Electrolyzed Water Immersion at Different Frequencies on Quality of Raw Chicken Legs.

Slightly acidic electrolyzed water (SAEW) is used as a disinfectant for raw chicken meat. Because its volume for a single immersion exceeds 10 times the weight of meat, a large amount of wastewater is generated. Importantly, a higher frequency of immersion is believed to reduce microbial contamination. The objective of this study was to investigate the effect of SAEW immersion at different frequencies on the disinfection and quality of raw chicken legs, thereby possibly limiting the usage of SAEW. Immersion for 1, 3, and 5 times, with a 7:1 SAEW:meat ratio, and duration of 15 min was tested. Meat quality was evaluated based on total aerobic bacteria, Enterobactericeae, total volatile basic nitrogen, thiobarbituric acid reactive substances, and color. A higher immersion frequency lowered the numbers of total aerobic bacteria and Enterobacteriaceae. Moreover, two immersions with a SAEW:meat ratio of 4:1 and a total immersion time of 6 min reduced the bacterial load as effectively as a single 15-min immersion with a SAEW:meat ratio of 7:1. Higher frequencies of SAEW immersion also resulted in lower total volatile basic nitrogen and lipid oxidation after 0 or 3 days of storage. They did, however, magnify the change in color, resulting in brighter meat. Overall, SAEW treatments with two to five immersions can improve the quality of raw chicken legs and reduce wastewater generation.

Eco friendly stability indicating HPTLC method for simultaneous determination of sofosbuvir and ledipasvir in pharmaceutical tablets and HPTLC-MS characterization of their degradation products

Recently, the analytical community has shown increasing interest in developing more environment-friendly practices by eliminating or reducing the use of hazardous chemicals and solvents which are extremely dangerous to human health and the environment. Thus in this study, a simple, rapid, inexpensive and eco-friendly HPTLC method with densitometric detection was designed, optimized and validated for the simultaneous quantitation of the antiviral drugs sofosbuvir (SOF) and ledipasvir (LED) in pure powder, synthetic mixtures, combined pharmaceutical formulation and in the presence of their stressed degradation products with high sensitivity and no interference. The separation was carried out on silica gel F254 plates, using green mobile phase ethyl acetate: water: ethanol (94:5:1v/v/v) for development followed by densitometric detection of SOF and LED at 250 and 320 nm, respectively. Both drugs had second order polynomial calibration curves within ranges 100–5000 ng/spot and 100–3000 ng/spot for SOF and LED, respectively, with correlation coefficients >0.9998 and the limits of detection were 30 and 29 ng/spot and the limits of quantification were 90 and 88 ng/spot for SOF and LED, respectively. The method was validated in terms of linearity, accuracy, precision, selectivity, and robustness. The drugs were subjected to acidic and basic hydrolysis, oxidation and photolytic conditions as per ICH guidelines, followed by detection of the degradation products and structure elucidation of their fragments with the aid of the HPTLC-ESI- MS technique. The greenness of the proposed method was assessed using the analytical Eco-Scale as an assessment tool with a 93-point score. So, it is considered excellent green.

Catalytic Conversion of Glycerol to Acetol and Acrolein Using Metal Oxides: Surface Reactions, Prospects and Challenges

AbstractGlycerol dehydration to acetol and acrolein is an interesting reaction pathway for conversion of biomass‐derived products. However, they undergo extensive deactivation due to coke deposition and sintering, requiring the design of stable catalysts. The oxides stand out due to their natural abundance, simple synthesis, low cost and tunable acidic, basic and redox properties. The different studies apply these oxides as pure phase, supported, mixed or doped. However, it is observed that despite the large number of applied oxides in glycerol conversion, few works describe in detail about more complex oxides such as ferrites, hexaferrites, perovskites, among others. This review reports different acid oxides in the glycerol dehydration to acetol and acrolein as well as basic and redox oxides, describing a historical perspective, showing the most important theoretical foundations of heterogeneous catalysis to comprehend surface reactions and mentioning the different possibilities to understanding the different reactional pathway, highlighting the proposal mechanisms that explain the participation of the different active sites on the surface reactions. Furthermore, the sequence of reactions which show the origin of the coke deposited on catalyst surface was presented, emphasizing the main challenges. The role of the Lewis and Brønsted acid‐base sites present in the metal oxides and their interactions on glycerol dehydration were described, providing a direction to design catalysts for selective dehydration reactions resistant against coke deposition and sintering.

Uncovering the effect of surface basicity on the carbon deposition of Ni/CeO2 catalyst modified by oxides in DRM

The acidity and basicity of Ni based catalysts play very important role in the catalytic performance during dry reforming of methane. Hence, the effects of surface basicity regulated by adding the oxides (CaO, MgO, ZnO and La2O3) in Ni/CeO2 catalysts on the catalytic behavior were systematically investigated, and the characterization methods and DFT calculations were performed to reveal the underlying mechanism. It was found that the addition of basic oxides could improve the activity and stability due to these oxides could increase the adsorbed oxygen, reduce the size of Ni particle and improve the interaction between Ni and support, in particular, the MgO interacts with Ni to form MgNiO2 spinel, which contribute to promote Ni dispersion and inhibit Ni aggregation. Moreover, the results suggested that the resistance to carbon deposition has something to do with the surface basicity. To a certain degree, the increasing the amount of basic site and enhancing alkaline strength could suppress the carbon deposition of Ni based catalysts. This is mainly because that the basic site is beneficial to CO2 adsorption and activation based the DFT calculations, which could accelerate the elimination of carbon deposition by provide more oxygen species. These results could provide some useful information to the design and synthesis of Ni-based catalysts.

Carbon dioxide removal from biogas through sorption processes using natural and activated zeolite adsorbents

ABSTRACT Natural zeolite is among the low-cost materials that can be used to remove contaminants in biogas. The cleaning of biogas increases its energy density and reduces possible negative effects. The current study aimed to upgrade biogas using natural zeolites. The activation of natural zeolite was done using sodium hydroxide. The adsorbent samples were characterised using an XRF machine, while the biogas samples were analysed using Shimadzu gas chromatography and a portable digital gas detector. The effect of zeolite-to-water ratio on the carbonation process was investigated. In addition, the effects of biogas flow rate, adsorbent dose and contact time on the dry adsorption process were studied. The maximum CO2 uptake of zeolite was 4.8 and 0.2 mmol/g by dry adsorption and wet carbonation process, respectively. The results indicate that surface adsorption favoured by a low Si2O3/Al2O3 ratio was more prominent than carbonation that requires high basic oxides. The results showed that an increase in the dose of activated clay from 2.5 to 35 g increased the removal efficiency of CO2 from 11.2% to 79.8%, while the CO2 uptake decreased from 4.8 to 2.5 mmol/g. Furthermore, the experimental data fitted best to pseudo-first-order kinetics and the Bohart-Adams model for the breakthrough curve.

Probing Capacity Trends in MLi2Ti6O14 Lithium-Ion Battery Anodes Using Calorimetric Studies.

Due to higher packing density, lower working potential, and area specific impedance, the MLi2Ti6O14 (M = 2Na, Sr, Ba, and Pb) titanate family is a potential alternative to zero-strain Li4Ti5O12 anodes used commercially in Li-ion batteries. However, the exact lithiation mechanism in these compounds remains unclear. Despite its structural similarity, MLi2Ti6O14 behaves differently depending on charge and size of the metal ion, hosting 1.3, 2.7, 2.9, and 4.4 Li per formula unit, giving charge capacity values from 60 to 160 mAh/g in contrast to the theoretical capacity trend. However, high-temperature oxide melt solution calorimetry measurements confirm strong correlation between thermodynamic stability and the observed capacity. The main factors controlling energetics are strong acid-base interactions between basic oxides MO, Li2O and acidic TiO2, size of the cation, and compressive strain. Accordingly, the energetic stability diminishes in the order Na2Li2Ti6O14 > BaLi2Ti6O14 > SrLi2Ti6O14 > PbLi2Ti6O14. This sequence is similar to that in many other oxide systems. This work exhibits that thermodynamic systematics can serve as guidelines for the choice of composition for building better batteries.

Steam reforming of bio-alcohols over Ni-M (Cu, Co, Pt)/MCF-S (MgO, La2O3, CeO2) for renewable and selective hydrogen production: Synergistic effect of MCF silica and basic oxides on activity and stability profiles

In the current investigation, highly active, and stable catalyst-support systems were developed by employing the benefits of the 3D mesoporous arrangement of MCF silica and O2− Lewis basic sites of MgO, La2O3, and CeO2 in a single system for renewable and selective H2 production via steam reforming (SR) of bio-alcohols, viz., ethanol (SRE), glycerol (SRG), n-butanol (SRB), and ethylene glycol (SREG). The impact of aging time [24, 48, and 72 h ] on structural and surface features of MCF silica was also investigated to develop novel type of mesoporous materials with the best textural properties, viz., Cu-Ni-Co/MCF-MgO for SRE, Ni-Cu/MCF-La2O3 for SRG, Pt-Ni-Cu/MCF-La2O3 for SRB and Ni-Cu/MCF-CeO2 for SREG which were characterized by several physio-chemical techniques; for instance, BET, H2-TPD, H2-TPR, TGA, XRD, TEM, SEM, EDX as well as high-resolution XPS analysis. The efficacy of the combination of MCF silica with basic metal oxides was evident from the results showing nearly complete reactant conversion, no coke formation, high selectivity (>84 % H2 yield), and long-term stability beyond 680 h (> 68 h time on stream (TOS) for one cycle over > 10 cycles) for all bio-alcohols whereas MCF silica without any basic metal oxides, i.e. Ni-Cu/MCF was stable only up to ≤ 64 h (≤ 16 h TOS for one cycle up to ≤ 4 cycles) due to the absence of O2− Lewis basic sites leading to coking. Such a huge difference in catalytic stability between MCF-S (MgO, La2O3, CeO2) and Ni-Cu/MCF catalysts clearly justifies the synergistic effect of the 3D mesoporous structure of MCF silica and O2− Lewis basic sites on high metal dispersion, strong metal-support interaction (SMSI), coke inhibition. It proved their efficacy as potential commercial SR catalysts for sustainable H2 production from bio-alcohols. Finally, catalytic reaction mechanisms were developed for SRE, SRG, SRB, SREG and intrinsic reaction kinetics were studied over their corresponding catalyst-support systems in the absence of external mass transfer and intra-particle diffusion resistancs. The apparent activation energies for SRE, SRG, SRB, and SREG were calculated as 7.2, 11.2, 10.5, and 12.1 kcal/mol, respectively.

Oxidation and wetting characteristics of lead-free Sn-0.7Cu solder alloys with the addition of Fe and Bi

In this paper, the oxidation and wetting behaviour of Sn-0.7Cu and Sn-0.7Cu-0.05Fe-2Bi solder alloys has been investigated. The alloys were subjected to 200 °C in oxygen rich environment. Weight gain curves reveal that the oxidation behaviour obey the parabolic rate law. X-Ray photo electron spectroscopy (XPS) reveals the presence of SnO and SnO2 oxide layer on the surface of Sn-0.7Cu solder alloys. SnO was formed as the basic oxide layer. However, at higher temperature SnO transforms into SnO2. Addition of Bi results in the formation of Bi2O3. The Pilling-Bedworth ratio of SnO, SnO2 and Bi2O3 oxides are 1.28, 1.35 and 1.23 respectively. These ratios confirm the passive nature of oxide layers. Wetting behaviour of Sn-0.7Cu and Sn-0.7Cu-0.05Fe-2Bi were investigated on Cu substrate. The addition of Bi and Fe improves the wetting properties of Sn-0.7Cu solder alloys. Alloying with Bi and Fe results in growth suppression of intermetallic compound at the interface. Increase in spreading rate, decrease in wetting angle and solder height reveals better performance of the Sn-0.7Cu-0.05Fe-2Bi solder alloy.