Addition Of Barium Research Articles

Experimental examination on physical and radiation shielding features of boro-silicate glasses doped with varying amounts of BaO

Investigations were conducted on the addition of barium's impact on the radiation shielding and physical attributes of five different glasses, designated S1–S5, with varying BaO contents. Using two point sources namely Co60 and Cs137 along with a scintillation detector [NaI(TL)], experimental measurements were made of the shielding parameters of γ-rays, namely the effective atomic number (Zeff), electron density (Nel), half-value layer (HVL), linear attenuation coefficient (μ), mass attenuation coefficient (μm), mean free path (λ), and radiation protection effectiveness at the energies of 0.664, 1.177, and 1.334 MeV, and comparisons made with recently considered glasses as well as frequently employed materials for γ-ray shielding. The results show that the examined glasses' physical and radiation shielding qualities are improved by the addition of BaO. The μ values increased from 0.245 to 0.275 cm−1 (0.662 MeV), from 0.174 to 0.198 cm−1 (1.173 MeV), and from 0.161 to 0.189 (1.332 MeV). The observed values of HVL decreased from 2.83, 3.98, and 4.3 cm to 2.5, 3.5, and 3.62 cm at 0.662, 1.173, and 1.332 MeV, respectively, for the samples S1 and S5. In addition, the S5 glass sample was determined to have the best protection against photon among all the samples that were evaluated, as well as against recently considered glasses and those materials often utilized for gamma-ray shielding purposes.

Advances in Lead-Barium-Zinc-Silicate-Type Glazed Warming Bowl Related to the Chinese Xuande Reign (1426–1435)

Diagnostic investigations were carried out on a rare Chinese polychrome glazed ceramic dating back to the reign of the Xuande Emperor (1426–1435). The double-walled warming bowl was investigated using several non-invasive methods such as portable optical microscopy, endoscopy, portable X-ray fluorescence spectrometry, X-radiography, and computed tomography. One microsample was collected and analyzed by scanning electron microscopy with an energy dispersive X-ray detector. According to the results, the chemical composition of the paste suggested a porcelain typology, while the glaze belongs to the lead–barium–silicate (PbO-BaO-ZnO-SiO2) system. These unexpected data contrast with common knowledge, which attests that the addition of barium in glass and ceramics manufacturing disappeared soon after the Han dynasty (206 BCE-220 CE). Moreover, the combination of PbO-BaO-ZnO-SiO2 seems to be quite rare both in ancient pre-Han times and during the Ming and Qing dynasties. This paper aims to demonstrate that (a) the use of barium for glaze and glass composition, which seems to have its roots in Taoist alchemy, was not totally halted in later periods compared to the Han dynasty; (b) lead–barium–zinc–silicate glaze was used during the Xuande Emperor’s reign. Through a review of ancient Chinese literary sources, we found a lot of unpublished information on the use of barium, lead, and zinc in the production of glazed ceramics during this period. The polychrome glazed warming bowl suggests a particular production that flourished during the brief reign of the Xuande Emperor.

Influence of alkaline earth metals on the corrosion-electrochemical behavior of lead babbit BKa, BSt, BBa (PbSb15Sn10) in NaCl electrolyte medium

The article presents the results of study of the effect of additions of calcium, strontium and barium (0.01–1.0 wt %) as a structure modifier on the anodic behavior of lead babbits BKa, BSt, BBa (PbSb15Sn10) in NaCl electrolyte medium. The studies were carried out by the potentiostatic method in a potentiodynamic mode with a potential sweep rate of 2 mV/s.Studies show that with time the free corrosion potential of alloys shifts to the positive side, and with an increase in the concentration of the modifier (calcium, strontium and barium) in lead babbits, acquires a positive value. The addition of calcium to lead babbit BKa (PbSb15Sn10Ca) increases its corrosion resistance by 10 – 15%, strontium BST (PbSb15Sn10Sr) by 15–20%, and barium BBa (PbSb15Sn10Ba) by 20–25%. An increase in the corrosion rate of alloys was noted, regardless of t heir composition from the NaCl concentration in the solution. It has been shown that an increase in the chloride ion concentration in the NaCl electrolyte leads to a decrease in the potentials of free corrosion, repassivation, and pitting formation of alloys.

Effect of Barium on the Corrosion and Electrochemical Behavior of Lead Babbit BBa (PbSb15Sn10Ba) in a NaCl Electrolyte Medium

Results are presented from studying the effect barium additives (0.01–1.0 wt %) as a structure modifier have on the anodic behavior of lead babbit BBa (PbSb15Sn10Ba) in a NaCl electrolyte medium. The studies are performed using the potentiostatic technique in the potentiodynamic mode with a potential sweep rate of 2 mV/s. It is shown that the free corrosion potential of alloys shifts to the positive side over time and acquires a positive value upon an increase in the concentration of the modifier (barium) in the lead babbit. Adding barium to lead babbit BBa (PbSb15Sn10Ba) raises its corrosion resistance by 20–25%. An increase in the rate of the corrosion of alloys is noted, regardless of their composition and the concentration of NaCl in a solution. It is shown that raising the concentration of chloride ions in a NaCl electrolyte lowers the potentials of the free corrosion, repassivation, and pitting of alloys.

Electrical and magnetic characteristics of barium doped bismuth ferrite via sol–gel auto combustion technique

This study is devoted to the preparation of barium doped bismuth ferrites by sol–gel auto combustion method using different concentrations of barium nitrates Bi1-xBaxFeO3 (x = 0, 0.10, 0.20, 0.30). The Electrical, structural properties, and crystallite size of all samples had been studied. The electrical properties, of the samples, showed compromising results to use in electrical applications. The X-ray diffraction analysis of the samples showed the rhombohedra shape of the samples. The crystallite size were measured and noted to be 24 nm with the enhancement of Ba concentration. The electrical conductivity and resistivity are measured by the mean of two probe methods and results showed an increase in conductivity with the addition of barium. The activation energy were also calculated and recorded to be a 2.07 eV. The magnetic susceptibility of all samples was measured and the response was enhanced by the increase of the Ba concentration. SEM study revealed the morphology of the all prepared samples. The nanoparticles have average particle sizes of 15 and 75 nm, were observed by using image software. The FTIR analysis of all samples resulted the transmittance and the functional group of the all samples.

CO Removal from Hydrogen Stream through Methanation on Ru/C Catalysts Doped with Lanthanum and Barium

The influence of the lanthanum and barium addition on the physicochemical properties and catalytic behavior of the Ru/C catalyst for CO methanation was investigated. The catalyst was doped with La or with La plus Ba. It was found out that there are various ways the additives were applied in the study, thus changing the catalytic performance of the basic material and influencing the susceptibility of the carbon support in relation to undesired methanation. The highest catalytic activity, 23.46 (mmol CO/gC+Ru × h), was achieved for the LaRu/C system, with methane selectivity exceeding 80% over the whole temperature range. Ba addition caused a significant decrease in activity. TG-MS studies revealed that both La and Ba improved the resistance of the carbon support to undesired methanation. Detailed characterization methods, employing XRPD, Raman spectroscopy, CO chemisorption, and SEM-EDX, showed that the catalytic behavior of the studied catalysts was attributed to lanthanum distribution over the Ru/C materials surface and structural changes in the carbon support affecting electron supply to the metallic active phase.

Co nanoparticles supported on mixed magnesium-lanthanum oxides: effect of calcium and barium addition on ammonia synthesis catalyst performance.

The synthesis of ammonia in the Haber-Bosch process produces millions of tons of ammonia annually needed for producing fertilisers required to feed the growing population. Although this process has been optimised extensively, it still accounts for about 2% of global energy consumption. It is, therefore, desirable to develop an efficient ammonia synthesis catalyst. Over the last decades, many attempts have been made to improve the ammonia synthesis catalyst efficiency under mild conditions. Here, we studied the effect of adding Ca and Ba to the cobalt ammonia synthesis catalyst. The combination of the different experimental results allows concluding that Ca served as an inactive additive, whereas Ba served as an electronic promoter. The Ca addition did not change the textural, structural, and chemisorptive properties of the Ca-doped Co catalyst. On the other hand, the Ba addition had a major effect on the nature of active Co sites. It contributed to the formation of new active sites for hydrogen and nitrogen adsorption and dissociation. Barium addition also contributed to the generation of new basic sites, particularly the strong ones. These unique characteristics were ascribed to the formation of Co(core)-BaO(shell) structures. It is likely that the donation of electrons from BaO to N2 via Co markedly promoted ammonia synthesis. This catalyst exhibited ammonia synthesis activity 4 times higher than that of the undoped Co catalyst and 2 times higher than that of the industrial Fe catalysts under identical conditions.

Promotion of Ru or Ni on Alumina Catalysts with a Basic Metal for CO2 Hydrogenation: Effect of the Type of Metal (Na, K, Ba).

Ru and Ni on alumina catalysts have been promoted with a 10 wt% of alkali metal (K or Na) or alkaline earth metal (Ba) and tested in CO2 methanation. For the catalyst consisting of Ni and Ba, the variation of Ba loading while keeping Ni loading constant was studied. The promotion in terms of enhanced CH4 yield was found only for the addition of barium to 15 wt% Ni/Al2O3. In contrast, K and Na addition increased the selectivity to CO while decreasing conversion. For the Ru-based catalyst series, no enhancement in conversion or CH4 yield was attained by any of the alkaline metals. CO2 temperature-programed desorption (CO2-TPD) revealed that the amount of chemisorbed CO2 increased significantly after the addition of the base metal. The reactivity of COx ad-species for each catalyst was assessed by temperature-programed surface reaction (TPSR). The characterization revealed that the performance in the Sabatier reaction was a result of the interplay between the amount of chemisorbed CO2 and the reactivity of the COx ad-species, which was maximized for the (10%Ba)15%Ni/Al2O3 catalyst.

Effect of barium additions on the thermophysical and thermodynamic properties of zinc alloy TsAMSv4-1-2,5

Application of zinc and zinc alloys as structural materials is due to their corrosion resistance properties. Zinc alloys are highly resistant to corrosion in air and in marine conditions, in low-density alkaline and acidic solutions, and they have good cutability. Heat capacity is one of the essential characteristics of zinc alloys. Heat capacity and its temperature dependence play a major role in alloy studies. The available literature does not provide any information about how the addition of barium changes the heat capacity of zinc alloy TsAMSv4-1-2,5. A study was conducted to understand the temperature dependence of the thermophysical properties and thermodynamic functions of the zinc alloy TsAMSv4-1-2,5 with barium. For this, cooling curves of the reference and studied samples were compared in the cooling mode in the temperature range of 300–500 К using a copper reference sample (A5N grade of Al). This heat capacity measurement technique is based on the Newton-Richman cooling law. It is demonstrated that the heat capacity, enthalpy and entropy of the zinc alloy tend to decrease with the addition of barium, whereas the Gibbs energy of the alloys increases. Heat intensifies the thermophysical and thermodynamic properties of the alloys. The information about the obtained thermophysical and thermodynamic parameters of the zinc alloy TsAMSv4-1-2,5 with barium adds to the corresponding thermophysics reference books and it can also be used when designing parts and machines from the above mentioned alloys.

Effect of Selected Cations and B Vitamins on the Biosynthesis of Carotenoids by Rhodotorula mucilaginosa Yeast in the Media with Agro-Industrial Wastes

In recent years, there has been an increase in the search for novel raw materials for the production of natural carotenoids. Among yeasts, Rhodotorula species have the ability to synthesize carotenoids, mainly β-carotene, torulene, and torularhodin, depending on the culture conditions. This study aimed to determine the effect of selected cations (barium, zinc, aluminum, manganese) and B vitamins (biotin, riboflavin, niacin, pantothenic acid) on the biosynthesis of carotenoids by Rhodotorula mucilaginosa MK1 and estimate the percentages of β-carotene, torulene, and torularhodin synthesized by the yeast. The cultivation was carried out in a medium containing glycerol (waste resulting from biodiesel production) as a carbon source and potato wastewater (waste resulting from potato starch production) as a nitrogen source. Carotenoid biosynthesis was stimulated by the addition of aluminum (300 mg/L) or aluminum (300 mg/L) and niacin (100 µg/L) to the medium. The number of carotenoids produced by R. mucilaginosa MK1 in the medium containing only aluminum and in the medium with aluminum and niacin was 146.7 and 180.5 µg/gd.m., respectively. This content was 101% and 147% higher compared to the content of carotenoids produced by yeast grown in the control medium (73.0 µg/gd.m.). The addition of aluminum and barium seemed to have a positive effect on the biosynthesis of torulene, and the percentage of this compound increased from 31.86% to 75.20% and 68.24%, respectively. Niacin supplementation to the medium increased the percentage of torularhodin produced by the yeast from 23.31% to 31.59–33.79%. The conducted study showed that there is a possibility of intensifying carotenoid biosynthesis by red yeast and changing the percentages of individual carotenoids fractions by adding cations or B vitamins to the medium. Further research is needed to explain the mechanism of action of niacin on the stimulation of torularhodin biosynthesis.

Evaluation of the influence of trace metals on methane production from domestic sewage, using the Plackett-Burman experimental design

Methanogenesis involves several enzymes with trace metal components that catalyze major metabolic pathways and, therefore, requires a sufficient supply of micronutrients such as iron, nickel or cobalt. The statistically-based Plackett-Burman experimental design was adopted in this study to identify which trace metal have a statistically significant effect on the maximum methane production from domestic sewage. The addition of Barium (Ba), Cobalt (Co), Copper (Cu), Iron (Fe), Manganese (Mn), Nickel (Ni) and Selenium (Se) was tested in batch reactors using domestic sewage as the substrate and sewage sludge as the inoculum. The results showed that the addition of Fe was statistically significant, positively affecting the maximum CH4 production (p-value 0.05). The results are expressed in L of CH4 per g of Chemical Oxygen Demand added, increasing it from 0.10 to 0.13 LCH4 gCODadd−1. In L of CH4 per g of Volatile Solids, increased it from 0.031 to 0.040 LCH4 gVS−1. The addition of Se was statistically significant, but with a negative effect on the maximum methane production (p-value 0.002), which decreased from 0.13 to 0.10 LCH4.gCODadd−1. Moreover, six different Fe concentrations (0, 40, 80, 120, 160 and 200 mgL−1) were tested, showing that the addition of 120 mgL−1 had the greatest effect for statistically improving the maximum methane production, with 33% improvement (0.12 ± 0.003 to 0.16 ± 0.012 LCH4 gCODadd−1) compared to no addition of Fe and the specific CH4 production to 0.040 ± 0.001 LCH4 gVS−1.

Dependence of the dielectric properties of barium titanate ceramics and a composite based on it on the sintering temperature

In this paper, we compare the structure and dielectric properties of the samples of barium titanate ceramics that have been sintered at temperatures of 1100, 1150, 1200, 1250 and 1350 °C and dielectric characteristics of the samples of barium titanate (80 vol.%) — barium ferrite (20 vol.%). It is shown that only samples sintered at the temperature of 1250 and 1350 °C have polarization sufficient for the existence of the piezoelectric effect. For the same samples, the pyroelectric coefficient and reversal polarization significantly exceed those for samples sintered at lower temperatures. Analysis of the samples structure confirmed the dependence of the dielectric properties of the barium titanate ceramics on the grain size and, as a consequence, on the sintering temperature. Based on the studies carried out, the optimal temperature (1250 °С) for obtaining composite samples of barium titanate (80 vol.%) — barium ferrite (20 vol.%) was selected. The temperature dependence of the dielectric constant for the composite samples based on barium ferrite — barium titanate with a sintering temperature of 1250 °C is similar to the dependence for the BaTiO3 ceramic samples sintered at 1350 °C. At room temperatures, the permittivity of the composite samples is also significantly higher than that of the barium titanate ceramic samples obtained at the same sintering temperatures. The addition of barium ferrite to the barium titanate not only increased the permittivity of the composite, but also led to a diffusing of the ferroelectric phase transition and a shift in the temperature of the maximum of the dielectric constant by 10 degrees towards high temperatures.

P0283 / #969: RHEOLOGICAL ANALYSIS OF LIQUIDS OFFERED IN VIDEOFLUOROSCOPY EXAM TO NEONATES AND INFANTS: A PRELIMINARY STUDY

Aims & Objectives: Objective The propose of this exploratory study was to know the behavior and macroscopic properties of untreated breast milk and infant formula, isolatedly and with barium sulfate added, providing information that can help speech-therapists and radiologists during the videofluoroscopy swallowing studies (VFSS). Methods: Method Rheological measurements were taken in an R/S+ Rheometer SST, SN 7023123, with a sample of regular infant formula; a sample of untreated breast milk; both isolated and with barium sulfate added, in the proportion of 2:1, respectively. Results: Results The breast milk and the infant formula have presented the adjusted viscosity similar between them, considered as thin liquid, according to the National Dysphagia Diet (NDD) classification (1.73 ± 0.12 cP and 1.53 ± 0.06 cP, respectively). The addition of barium in the proportions used in this study increased the viscosities of untreated breast milk 18 times, from 1.73 ± 0.12 cP to 31.30 ± 0.32 cP, and of the formula 25 times, from 1.53 ± 0.06 to 38.31 ± 2.19 cP, reaching thresholds close to that of nectar. Conclusions: Conclusion The results indicated confirm the need of knowledge and care in preparing liquids to be offered in pediatric VFSS, especially with neonates and infants. The use of liquids in consistency and viscosity as close as possible to what will be proposed in the indication of the patient’s diet is fundamental for their safety, thus contributing for clinical decision-making and speech-language practice. This will guarantee more confidence that VFSS represents the infant swallow function, minimizing risks on their treatment.

Influence of barium addition on the formation of primary Mg2Si crystals from Al–Mg–Si melts

In this study, the influence of different contents of Ba additions on the microstructure evolution, phase reaction characteristic, and mechanical property of Al–Mg–Si alloy was investigated. Microstructural characterization was conducted by means of scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) facility, X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). The mechanical property was examined using hardness test. The results revealed that cubic primary Mg2Si crystals shaped by {100} facets with an average particle size of 35 μm were successfully fabricated through the addition of 0.2 wt. % Ba element to Al–Mg–Si melts. For the first time, it is revealed that the Al4Ba compound can act as the nuclei for the primary Mg2Si during solidification, which leads to the refining of the primary Mg2Si particle size extensively. Furthermore, the formation of Al2Si2Ba and AlSiBa intermetallic compounds (IMCs) are liable for the Mg2Si particle refinement; hence, the hardness of the alloy increased from 60.21 to 67.83 Hv. Besides, thermal analysis showed that the nucleation temperatures of the primary Mg2Si phase increased with the addition of Ba. Ba additions perform a substantial role in determining the shapes of primary Mg2Si crystals, which can be altered from coarse dendritic structure (0 wt. %) to crystals with a combination of eight {111} and four {100} facets (0.08 wt. %), then to truncated cube (0.1 wt. %), and finally to a cube fully bounded by {100} facets (0.2 wt. %) with increasing Ba concentrations. This study revealed that the growth process of the cubic primary Mg2Si is due to the absorption and poisoning effect of Ba atoms, which leads to the fading of the growth rates of {100} faces of primary Mg2Si and as a result the {100} faces are exposed. Furthermore, in the modified alloy, the skeleton-type growth process of the cubic primary Mg2Si was found, in which growth steps with some hillocks were detected.

Effect of Barium Addition on Hydrolytic Enzymatic Activities in Food Waste Degradation under Anaerobic Conditions

Enzymatic hydrolysis of complex components of residual materials, such as food waste, is a rate-limiting step that conditionates the production rate of biofuels. Research into the anaerobic degradation of cellulose and starch, which are abundant components in organic waste, could contribute to optimize biofuels production processes. In this work, a lab-scale anaerobic semi-continuous hydrolytic reactor was operated for 171 days using food waste as feedstock; the effect of Ba2+ dosage over the activity of five hydrolytic enzymes was also evaluated. No significant effects were observed on the global performance of the hydrolytic process during the steady-state of the operation of the reactor, nevertheless, it was detected that Ba2+ promoted β-amylases activity by 76%, inhibited endoglucanases and α-amylases activity by 39 and 20%, respectively, and had no effect on β-glucosidases and glucoamylases activity. The mechanisms that rule the observed enzymatic activity changes remain unknown; however, the discussion in this paper provides hypothetical explanations for further research.

Synergistic Interaction of Cerium and Barium-New Insight into the Promotion Effect in Cobalt Systems for Ammonia Synthesis

This study explains a co-promoting interaction of cerium and barium additives in a cobalt catalyst used for ammonia synthesis. The results show that a synergistic effect of Ce and Ba promoters in the catalyst is associated with an emergence of a third promoter—BaCeO3—which forms in situ from its individual components during catalyst activation. The influence of perovskite-type barium cerate is substantial due to its strong basic properties, i.e. high electron-donating ability and a tendency to stabilize the Co hcp cobalt phase (more active in ammonia synthesis than the Co fcc phase). BaCeO3 diversifies the structure of adsorption sites on the cobalt surface by contributing to the exposure of facets with more favourable adsorption and binding energies with regards to rate-limiting reactions steps. It allows to a more fluent formation and transfer of species unrestricted by the hydrogen or product poisoning consequently accelerating the entire ammonia synthesis process.

Red-mud based porous nanocatalysts for valorisation of municipal solid waste

Red mud samples were used to catalyse in-situ co-pyrolysis of pinewood and low-density polyethylene for the production of high-quality bio-oil. The sodium cation in the crude red-mud was exchanged with barium and calcium cations and further tested to explore their role in oil upgrading. The relationship between red-mud catalytic activity and its constituents was explored using synthetic sodalite. The red-mud catalysts exhibited a considerable aromatisation capacity compared to the thermal co-pyrolysis, as the selectivity towards monocyclic aromatic hydrocarbons increased from 12.7 to 19.6%, respectively. Long-chain molecules cracking was more significant in synthetic sodalite associated with their acidic active sites. The addition of barium and calcium cations to the red-mud largely improved oxygen elimination as a result of the enhanced catalyst basicity. In contrast, the aromatisation ability of red-mud significantly impeded by the large cation size (Ba2+ and Ca2+) due to the limited diffusion of pyrolysis vapours to the active sites. Ba-exchanged red-mud catalysts reduced the content of carboxylic acids in the bio-oil to 1.8 % while maintained a high yield of the organic fraction (34 %). Ca-exchanged red-mud catalysts produced the lowest fraction of oxygenated compounds (35.1 %); however, the organic phase yield was as low as 23.6 %. The modified red-mud catalysts reduced the fraction of oxygenated compounds from 69.9–35.1% during the biomass-plastic co-pyrolysis.

Radiopacity of computer-aided design/computer-aided manufacturing composite resin blocks.

This study aimed to clarify the degree of difference in radiopacity between sixteen CAD/CAM composite resin blocks, one ceramic block, and teeth of the same thickness on radiographs. The radiographic density of CAD/CAM composite resin blocks was measured and the results were compared with the corresponding values for enamel and dentin. Additionally, the study analyzed the constituent elements of each type of CAD/CAM composite resin block and conducted an examination to identify those elements exerting an influence on radiopacity. Compared to the enamel, there were five blocks with significantly higher radiopacity, two blocks with the same level in radiopacity, and ten blocks with notably lower radiopacity. Compared to the dentin, there were ten blocks with significantly higher radiopacity, one block with the same level in radiopacity, and six blocks with notably lower radiopacity. All of the CAD/CAM composite resin blocks for molars contained barium and strontium.This result suggests that the addition of heavy metals, for example, barium, strontium, and zirconium, would be effective in providing CAD/CAM composite resin blocks with radiopacity.

КИНЕТИКА ОКИСЛЕНИЯ АЛЮМИНИЕВОГО СПЛАВА АК12М2, МОДИФИЦИРОВАННОГО БАРИЕМ, В ТВЕРДОМ СОСТОЯНИИ

The oxidation kinetics of the AK12M2 aluminum alloy modified to 1.0% by barium was studied using thermogravimetry method. It was shown that the addition of barium to the alloy and the increase in temperature increase the oxidation rate of the initial alloy in the solid state. The apparent activation energy of the oxidation process of the AK12M2 aluminum alloy is 127.73 kJ/mol and decreases to 71.85 kJ∕mol for the alloy with 1.0% barium. The oxidation curves of the AK12M2 aluminum alloy with barium in the solid state are described by polynomials indicating the hyperbolic mechanism of that process. The mechanism of influence of barium on the oxidability of the AK12M2 aluminum alloy was established. It lies in the fact that barium in the range of 0.3-1.0% plays a dominant role in the formation of an oxide film, which is characterized by low protective properties. Barium influence is explained by its physicochemical properties as one of the alkaline earth metals.

Steam reforming of acetic acid over Ni–Ba/Al2O3 catalysts: Impacts of barium addition on coking behaviors and formation of reaction intermediates

Abstract The influence of barium addition to a Ni/Al2O3 catalyst on the reaction intermediates formed, the activity, resistance of the catalyst to coking, and properties of the coke formed after acetic acid steam reforming were investigated in this study. The results showed the drastic effects of barium addition on the physicochemical properties and performances of the catalyst. The solid-phase reaction between alumina and BaO formed BaAl2O4, which re-constructed the alumina structure, resulting in a decrease in the specific surface area and an increase in the resistance of metallic Ni to sintering. The addition of barium was also beneficial for enhancing the catalytic activity, resulting from the changed catalytic reaction network. The in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study of the acetic acid steam reforming indicated that barium could effectively suppress the accumulation of the reaction intermediates of carbonyl, formate, and C=C functional groups on the catalyst surface, attributed to its relatively high ability to cause the gasification of these species. In addition, coking was considerably more significant over the Ba–Ni/Al2O3 catalyst. Moreover, the Ba–Ni/Al2O3 catalyst was more stable than the Ni/Al2O3 catalyst, owing to the distinct forms of coke formed (carbon nanotube form over the Ba–Ni/Al2O3 catalyst, and the amorphous form over the Ni/Al2O3 catalyst).