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Palm oil fuel ash (POFA) and eggshell (EG) were explored towards efficient methylene blue (MB) removal. Calcined EG, with a high content of CaO was used as a low-cost activation replacement for the alkali treatment of POFA. The adsorption performance of EG–POFA was studied by comparing its performance with untreated POFA, calcined EG and commercially treated Ca–POFA, and the competency was following the order of EG ≈ Ca–POFA, indicating that EG effectively enhanced the efficiency of POFA. The response surface methodology (RSM) was executed to optimize the operating conditions of MB adsorption onto EG–POFA by investigating the effect of EG–POFA dosage ( X 1 ), initial pH ( X 2 ) and initial MB concentration ( X 3 ) towards MB removal (Y). X 1 = 1 . 18 g/L, X 2 = 6 , and X 3 = 182 mg/L, with Y = 80 .36% were found to be optimal conditions. The experimental data disclosed that the MB adsorption onto EG–POFA was in accordance with the Langmuir isotherm model ( q m = 714 . 29 mg/g) and followed pseudo-second-order kinetic model. The thermodynamic study discovered the endothermic and spontaneous natures of MB adsorption onto EG–POFA. This study discovered the feasibility of EG as an eco-friendly activation alternative for the alkali treatment towards remarkable MB adsorption.

This paper describes a study of the nature of metal-free protonated fibrous silica BEA (HSi@BEA) and its ability to generate protonic acid sites originating from molecular hydrogen and from C6 alkanes and cycloalkanes. HSi@BEA was successfully synthesized by a microemulsion system and subsequently applied in n-hexane, cyclohexane and methylcyclopentane isomerization. The HSi@BEA consisted of microspheres with a bicontinuous concentric lamellar structure morphology. Its core was mainly composed of an aluminosilicate framework of BEA, while the lamellar structure consisted of silica. The particle size of HSi@BEA was in the range of 400 nm to 700 nm with pore diameters between 3.6 nm to 5.6 nm and 15 nm to 25 nm. 27 Al MAS NMR results showed that the additional silica lamellar structure of the HSi@BEA increased the extra-framework aluminum (AlOH) which acts as Lewis acidic sites in the catalyst. FTIR results revealed that these additional Lewis acid sites in the metal-free catalyst generated a high amount of protonic acid sites by playing a role as electron acceptors after the dissociation of H2 and C6 alkane and cycloalkanes. Significantly, the participation of more protonic acid sites enhanced the catalytic performance of the C6 alkanes and cycloalkanes, n-hexane, cyclohexane and methylcyclopentane, at a low reaction temperature of 423 K. The presence of a silica lamellar structure resulted in a two to threefold higher isomer yield of n-hexane, cyclohexane and methylcyclopentane compared to bare HBEA catalyst which mainly produces cracking products. In addition, a kinetics study showed that the activation energy could be lowered by two to three times at elevated temperatures in the range of 423 K to 623 K.

A series of magnetite nanoparticles were prepared with electrosynthesis. Natural capping agent, sodium alginate (SA) was added to electrolysis system to produce smaller size and highly crystalline of magnetite. The variation of SA content highly influenced the particle size which confirmed with XRD. FTIR characterization confirmed that SA interact with magnetite surface. The magnetite product was also evaluated for paracetamol (PCT) degradation as a sample of pharmaceutical waste due to its large consumption in society. The highest initial degradation rate (8.22 x 10-2 mg/L.min) was achieved with magnetite which is prepared from 0.05% w/v of SA at initial concentration of 15 mg/L PCT. Finally, the result could contribute to electrosynthesis advancement of magnetite with high purity using inexpensive and green chemicals.

Fibrous silica beta zeolite (FSB) catalysts, which are excellent catalytic materials for petrochemical processes, were prepared by a microemulsion system assisted by commercial beta zeolite (BEA) seed crystallization under different urea/tetraethyl orthosilicate (urea/TEOS) ratios, denoted as 0.5:1-FSB, 1:1-FSB and 1:0.5-FSB. The physicochemical properties of the catalysts were investigated by XRD, MP-AES, FESEM, TEM, N2 physisorption and FTIR. The characterization results revealed that the dendrimeric silica fibers surrounding the BEA core shell of FSB were improved when the urea/TEOS ratio was altered, particularly for the ratio of 1:1. The highest terminal silanol and silanol nest intensities further confirmed its highest density of dendrimeric fibers. The catalytic testing of toluene methylation at 673 K resulted in the following order of p-, o- and m-xylene production ratio: 1:1-FSB (6/2/0) > 0.5:1-FSB (6/4/4) > 1:0.5-FSB (2/1/1). The catalyst with denser dendrimeric fibers led to lower acidity and pore volumes, which assist in selectively producing p-xylene and limiting the formation of side products. The FSB with denser dendrimeric fibers was also found to have a slower internal mass transfer rate, which is directly proportional to the activation energy. Optimization by the response surface methodology showed that the reactant molar ratio and reaction temperature were significant factors in the toluene methylation. The remarkable performance of these catalysts in the toluene co-reaction with methanol highlights their potential as future catalysts in the industrial application of toluene methylation and other chemical processes.

Application of CO2 methanation, especially in CO2-rich gas fields, could potentially provide additional value to the synthetic natural gas production. In this study, highly active vanadium (V2O5)-promoted Ni/KCC-1 catalysts with 5% nickel content were prepared using a co-impregnation method for CO2 methanation reaction. The influence of V2O5 on the textural properties, basicity and reducibility of the 5Ni/KCC-1 catalysts was systematically investigated. It was found that addition of V2O5 enhances the basicity of the catalysts; however, it decreases the surface area and pore volume. The amphoteric properties of V2O5 provide additional adsorption sites of CO2 producing more reactive unidentate CO2 adsorbed species. The presence of V2O5 also improved the dispersion and exposed more Ni species. This leads to an increased amount of reducible NiO species. Compared to 5Ni/KCC-1, the V2O5-Ni/KCC-1 series were active at lower temperature. The light off temperature for V2O5-Ni/KCC-1 was 423 K compared to 473 K for 5Ni/KCC-1. At 623 K, the 7.5V2O5-Ni/KCC-1 reaches 94.4% CO2 conversion, 15% higher than 5Ni/KCC-1. The presence of O2 negatively affects the catalytic activity as O2 interferes with the CO2 adsorption sites. The analysis of variance (ANOVA) indicates that the reaction temperature heavily influences the CH4 yield followed by the reduction temperature and H2 : CO2 ratio. The optimized conditions by the RSM are a reduction temperature of 696.9 K, a reaction temperature of 766.5 K and a H2 : CO2 ratio of 5.1.

The activity of mesoporous Al-MCM-41 for deoxygenation of

Catalytic CO

Carbon monoxide (CO) is the most harmful pollutant in the air, causing environmental issues and adversely affecting humans and the vegetation and then raises global warming indirectly. CO oxidation is one of the most effective methods of reducing CO by converting it into carbon dioxide (CO2) using a suitable catalytic system, due to its simplicity and great value for pollution control. The CO oxidation reaction has been widely studied in various applications, including proton-exchange membrane fuel cell technology and catalytic converters. CO oxidation has also been of great academic interest over the last few decades as a model reaction. Many review studies have been produced on catalysts development for CO oxidation, emphasizing noble metal catalysts, the configuration of catalysts, process parameter influence, and the deactivation of catalysts. Nevertheless, there is still some gap in a state of the art knowledge devoted exclusively to synergistic interactions between catalytic activity and physicochemical properties. In an effort to fill this gap, this analysis updates and clarifies innovations for various latest developed catalytic CO oxidation systems with contemporary evaluation and the synergistic relationship between oxygen vacancies, strong metal-support interaction, particle size, metal dispersion, chemical composition acidity/basicity, reducibility, porosity, and surface area. This review study is useful for environmentalists, scientists, and experts working on mitigating the harmful effects of CO on both academic and commercial levels in the research and development sectors.

As one of the potential bionanomaterials, nanocellulose has appeared as a favorable candidate for photoremediation of the environment because of its abundance in nature, inexpensive, eco-friendly, decomposable, high surface area, and outstanding mechanical properties. The current review carefully summarized the diverse type of nanocellulose, their preparation approaches, and several previous works on the use of nanocellulose for photoremediation. These include the role of nanocellulose for the increased surface active site of the hybrid photocatalysts by providing a large surface area for enhanced adsorption of photons and pollutant molecules, as a dispersing agent to increase distribution of metal/non-metal dopants photocatalysts, as well as for controlled size and morphology of the dopants photocatalysts. Furthermore, the recommendations for upcoming research provided in this review are anticipated to ignite an idea for the development of other nanocellulose-based photocatalysts. Other than delivering beneficial information on the present growth of the nanocellulose biomaterials photocatalysts, this review is expected will attract more interest to the utilization of nanocellulose photocatalyst and distribute additional knowledge in this exciting area of environmental photoremediation. This could be attained by considering that a review on nanocellulose biomaterials for environmental health photoremediation has not been described elsewhere, notwithstanding intensive research works have been dedicated to this topic.

Traditional fossil fuels emissions (mainly COx, SOx, and NOx) have adverse effects on human health and the atmosphere. As part of the clean use of fossil fuels, substitute natural gas (SNG) appears to be one of the most promising alternatives to coal and petroleum for its high combustion heat and low CO2 emissions. SNG can be produced using the catalytic methanation of carbon monoxide (CO). Still, the lack of a competitive and robust catalytic system is a significant challenge in CO methanation technology marketing. To emphasize enhanced catalytic CO methanation, this work offers a vital understanding of the extrinsic and intrinsic interactions between catalytic gears (active metals, support materials, and promoters). A contemporary evaluation has been made of the latest developments in CO methanation catalytic systems and the optimum synergistic relationship of active metals, support materials, and promoters. The influence of various active metals, supporting materials, promoters, synthesis methods, and reaction mechanisms studies were specifically compared and clarified to design effective CO methanation catalysts. This study can serve as a critical reference, contributing to the development of well-designed and appropriate catalysts for future applications and favorable dissemination performance in the various academic and industrial sectors.

Photo-fermentation biohydrogen production is an eye-catching and environmentally friendly route that can be excellently performed at ambient conditions. Nevertheless, light conversion efficacy and photo-fermentation hydrogen production performance are still low, and hence, numerous approaches are explored to enhance biohydrogen production. This review is intended at describing comprehensive characteristics and general mechanism of photo-fermentation biohydrogen production and highlights the advantages of this approach over other methods. Moreover, various pretreatment procedures of potential lignocellulosic biomass feedstocks for enhanced photo-fermentation biohydrogen production including physical, chemical, physical-chemical, and biological methods were elaborated thoroughly. Several crucial factors affecting photo-fermentation biohydrogen production such as the impact of pH, mixing, stirring, and lighting conditions, substrate concentration, different pretreatment conditions, and diverse fermentation modes were also discussed comprehensively. This aims to emphasize the recent advances in this field for further enhancement of biohydrogen production via photo-fermentation of lignocellulosic biomass. Additionally, the major challenge and prospects are also included to uncover the unexplored criteria of an effective and greener photo-fermentation biohydrogen production.

Biohydrogen produced from cellulosic feedstock is a promising candidate for future energy needs as a renewable energy carrier. The thermochemical route and biological processes have great potential for biohydrogen production. In particular, pyrolysis/gasification and dark fermentation are the methods to enhance the biohydrogen production from cellulose. The review compiles the essential information on both processes, including pretreatment of cellulose since it has a complex structure. The operating conditions for both processes, for example, the influence of cellulose pyrolysis/gasification such as temperature, heating rate, and vapor residence time, while for dark fermentation, including the temperature, inoculum source, hydraulic retention time, and pH, are discussed. The bioreactor configurations and economic aspects of both processes are also discussed. The review aims are to present the current state of knowledge about the two processes using cellulose as substrates. Surprisingly, dark fermentation is a promising method for application of cellulose for biohydrogen production since many works were done on dark fermentation compared to pyrolysis/gasification. The future perspectives on enhancing hydrogen production from cellulose have also been discussed.

Zinc oxide (ZnO) nanoparticles in the presence of fibrous silica (KCC-1) were produced via simple and green precipitation method. The nanoparticles properties were characterised with Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning electron microscopy (FESEM). It is believed that the preparation method influences on the characterization result. Based on nanoparticles characterisation, the properties of the chemical bond and nature of ZnO/KCC-1 and KCC-1 photocatalyst were analyzed by using Fourier Transform Infrared Spectroscopy (FTIR) that produced an infrared absorption spectrum. While, the morphology, dimension and particle surface area were observed by using Field Emission Scanning electron microscopy (FESEM).

Multiple contaminants including heavy metals and phenolic compounds are normally co-exist in wastewater, which caused the treatment process is rather complicated. Herein, the synergistic photoredox of Cr(VI) and p-cresol (pC) by innovative fibrous silica zirconia (FSZr) photocatalyst was reported. The high surface area of FSZr comprised of microspheres with a bicontinuous concentric lamella structure morphology consisted of silica, while its core consisted of ZrO2 structure. The rearrangement of FSZr framework increased the crystallinity, formed Si-O-Zr bonds and narrowed the band gap of ZrO2 for enhanced of photoredox of Cr(VI) and pC. Compared to the reaction, the photoredox efficiency of FSZr for removing Cr(VI) and pC in simultaneous system was found to be 96 % and 59 %, respectively which are higher than that in its single system owing to the efficient electron-hole charge separation. Phenolic compound with high degree of electron donating group gave beneficial effect to photoreduction of Cr(VI). Consequently, a proposed mechanism involving multi-photoredox pathway were proposed based on photoredox reaction and scavengers studies. FSZr sustained the simultaneous photoredox activities after five runs demonstrating its possibility to be use in the wastewater treatment of various pollutants.

Ethanol steam reforming (ESR) has recently appeared as a prominent, sustainable and green technology for large-scale hydrogen production as this process can convert sustainable ethanol feedstock originated from biomass to a standalone hydrogen fuel with great energy capacity about 120.7 kJ/g. Although hydrogen generated from ESR could be efficiently implemented for fossil fuel replacement, the heterogeneous catalytic ESR encounters several challenges associated with active metal sintering and carbonaceous deposition inducing catalyst deactivation. Hence the rigorous research on catalyst design, operation conditions, and mechanistic pathways are vital for enhancing catalyst stability, process optimization, kinetic modeling, and reactor design. This chapter summarizes the recent advances in catalytic ESR process for achieving high hydrogen yield and better ethanol conversion via catalyst design (including the suitable selection of active metals, supports, and promoters) and the adjustment of process variables, namely, temperature, gas hourly space velocity, and. Besides, ESR mechanistic routes and the corresponding fundamentally derived kinetic models for estimating the associated kinetic parameters are included in this chapter.

Syngas, a mixture of carbon monoxide and hydrogen, has recently emerged as an important intermediate feedstock in petrochemical industry and an efficient and eco-friendly energy carrier to substitute petroleum-based fuels. Although methane is conventionally employed as a main feedstock for syngas production via industrial methane steam reforming process, a rising interest about the implementation of glycerol for generating syngas is widely reported in literature due to its great abundance, low cost, and hydrogen-rich content. This chapter summarizes the recent progress in catalytic steam reforming of glycerol for syngas yield in terms of catalytic design using various supports and promoters and the manipulation of operating variables. The mechanistic pathways and their fundamentally derived kinetic models for expressing glycerol reaction rate and estimating associated kinetic parameters are also comprehensively reviewed throughout this chapter.

Recently, hetero junction materials (p-n-p and n-p-n) have been developed for uplifting the visible light activity to destroy the harmful pollutants in wastewater. This manuscript presents a vivid description of novel n-p-n junction materials namely CeO2-PPy-ZnO. This novel n-p-n junction was applied as the photocatalyst in drifting the mobility of charge carriers and hence obtaining the better photocatalytic activity when compared with p-n and pure system. Such catalyst's syntheses were successful via the copolymerization method. The structural, morphological and optical characterization techniques were applied to identify the physio-chemical properties of the prepared materials. Additionally, the superior performance of this n-p-n nanostructured material was demonstrated in the destruction of micro organic (chlorophenol) toxic wastes under visible light. The accomplished ability of the prepared catalysts (up to 92% degradation of chlorophenol after 180 min of irradiation) and their profound degradation mechanism was explained in detail.

Nanostructured photocatalysts commonly offered opportunities to solve issues scrutinized with the environmental challenges caused by steep population growth and rapid urbanization. This photocatalyst is a controllable characteristic, which can provide humans with a clean and sustainable ecosystem. Over the last decades, one of the current thriving research focuses on visible-light-driven CeO2-based photocatalysts due to their superior characteristics, including unique fluorite-type structure, rigid framework, and facile reducing oxidizing properties of cerium's tetravalent (Ce4+) and trivalent (Ce3+) valence states. Notwithstanding, owing to its inherent wide energy gap, the solar energy utilization efficiency is low, which limits its application in wastewater treatment. Numerous modifications of CeO2 have been employed to enhance photodegradation performances, such as metals and non-metals doping, adding support materials, and coupling with another semiconductor. Besides, all these doping will form a different heterojunction and show a different way of electron-hole migration. Compared to conventional heterojunction, advanced heterojunction types such as p-n heterojunction, Z-scheme, Schottky junction, and surface plasmon resonance effect exhibit superior performance for degradation owing to their excellent charge carrier separation, and the reaction occurs at a relatively higher redox potential. This review attends to providing deep insights on heterojunction mechanisms and the latest progress on photodegradation of various contaminants in wastewater using CeO2-based photocatalysts. Hence, making the CeO2 photocatalyst more foresee and promising to further development and research.

A severe problem associated with combustion of fossil fuels and biomass in the quest for heat and power generation is the release of acidic gases. This posed great health and environmental concerns, and their presence in sufficient amount in flue gas affects the performance of CO2 capture system through formation of heat resistant salts on reaction with the capture medium. Among the various alternatives, removal of the SO2 and NOx gases by adsorption on surface modified activated carbon from renewable sources has proven to be an efficient and robust technology which is attributed to the presence of immobilized chemical species on the carbon surface providing the necessary affinity with the target gaseous pollutants. Thus, the present review aimed at providing a cutting-edge critical assessment of research outputs on SO2 and NOx adsorption from flue gas by surface modified activated carbon. Conspicuously, modification mechanisms, surface characterization, surface chemistry and application of surface modification of activated carbon were discussed elaborately.

Fibrous silica ZSM-5 (FSZ) was synthesized by a microemulsion method, and subsequent incorporation of 5 wt% of TiO2 onto it via electrolysis in varying concentrations of supporting electrolyte tetraethylammonium perchlorate (TEAP) gave TFSZ catalysts. The results verified that the degree of desilication and dealumination, for increasing the insertion of Ti ions into the FSZ framework, was directly proportional to the concentration of TEAP. In parallel, impurity levels of Si O Ti bonds, defect sites and oxygen vacancies were formed and enhanced the photodegradation of paracetamol (PCT). However, excess Si O Ti interactions, as a consequence of a higher degree of desilication and dealumination, decreased the number of oxygen vacancies and surface defects, resulting in a higher band gap energy. The sequence towards the degradation of PCT was in the following order: 0.2-TFSZ (96%) > 0.1-TFSZ (88%) > 0.3-TFSZ (67%). The kinetics study followed the pseudo-first-order Langmuir–Hinshelwood model. The response surface methodology revealed that the initial concentration of PCT, catalyst dosage and pH were the significant factors in the degradation of PCT. The 0.2-TFSZ maintained the photocatalytic activities after five runs and able to degrade other endocrine disrupting chemicals efficiently, indicating its potential use in the wastewater treatment of those chemicals.

Dendrimeric fibrous silica HZSM-5 (HFSZ) catalysts were prepared using a microemulsion technique and ZSM-5-seeding crystallization with different oil phases, benzene, toluene, and xylene, and denoted as FB, FT, and FX, respectively. The HFSZ catalysts possessed a well ordered crystalline structure with chestnut-like spherical particles, rich with dendrimeric fiber morphology. It was found that the hydrophobicity of the oil phase significantly affected the physicochemical properties of the HFSZ catalysts that altered their activity toward benzene methylation. The density of dendrimeric fibers and ensuing acidities were found to play crucial roles in enhancing the selective production of toluene and p-xylene via transalkylation and dealkylation of bulkier aromatics. The production of ethylbenzene (EB) using commercial HZSM-5 could be suppressed to give major products of toluene (84%) and p-xylene (58%) when using FB and FX at 673 and 623 K, respectively.

The abundance presence of CO2 released into the atmosphere has gained numerous consideration for an effective method to mitigate the CO2 build up and recycling the carbon resource. Among the catalytic reactions, the methanation of CO2 has been an indispensable reaction to transform toxic CO2 into methane which can be use as energy carrier or valuable chemical. The application of heterogeneous catalyst in CO2 methanation plays a significant role due to its effectiveness and stability which led to lower costs for large scale production. This article discussed the recent developments of silica based catalyst for CO2 methanation with emphasized on its physicochemical properties and catalytic performance. In summary, the nature of silica support material such as morphology, textural properties and nature of basicity has a great influence on its catalytic performance towards CO2 methanation.

Zirconium-loaded mesostructured silica nanoparticles (Zr/MSN) were developed for the removal of hexavalent chromium (Cr(VI)) from aqueous solutions. X-ray diffraction, transmission electron microscopy, and Brunauer–Emmett–Teller results revealed that both MSN and Zr/MSN showed a characteristic highly ordered hexagonal pore structure with a high specific area of 821–1219 m2 g–1. Fourier transform infrared analysis showed that the presence of Zr diminished the absorbance band that was assigned to silanol groups of the structural defect sites, while XPS analysis of the binding energy of Si–O–Zr indicated interactions between the silanol groups and zirconium. The interaction of zirconium and silanol groups from the structural defect sites generated bidentate zirconium, which acted as an active site for the adsorption. The experimental results showed that the modification of MSN with zirconium significantly enhanced the adsorption capacity for Cr(VI). The equilibrium isotherm data showed that the adsorption pr...

Fugitive emissions are unavoidable releases that occur continuously throughout a process plant or wherever there are connections or seals between the process fluids and the external environment. The daily exposure of workers to such emissions, typically spread across an entire chemical plant, poses a serious threat to their health and safety. Previous works have focused on assessing the occupational health risks in chemical plants through indexes such as the inherent occupational health index and the integrated inherent safety index. The indexes serve as good proxy indicators for potential sources of occupational hazards (chemicals, process conditions) and process equipment. However, by considering the Source-Path-Receptor (SPR) model, the eventual health risk is also dependent on the path and receptor, where a potential leakage and exposure can occur, respectively. Typically, chemical plants are fitted with controls and mitigation measures known as protection layers (PL) to control hazards. Hence, the occupational health risks in chemical plants due to fugitive emissions require a more holistic methodology for assessment and evaluation. Therefore, a hybrid framework for assessing the occupational health risks from fugitive emissions was developed by adopting and integrating the concepts of source-path-receptor, layers of protection and hierarchy of control. The generic protection layers identified were classified according to the traditional hierarchy of controls. At the source, the protection layers identified were hazard elimination/substitution, inherently safer design, and engineering controls. Next, the maintenance and equipment reliability were identified as PL along the exposure path. Finally, at the receptor, worker-exposure was linked to management systems, procedural safety behaviour and culture. Therefore, the proposed methodology can be used for benchmarking and performance tracking of occupational health risk in a chemical plant over time, as the methodology includes the time-varying parameters of plant maintenance, management system compliance, safety behaviour and culture.

Silica-doped tetragonal mesoporous zirconia nanoparticles (SZ) were successfully synthesized with various concentrations of ammonia solution(NH4OH) using microwave-assisted method for photodegradation of Bisphenol A (BPA). The phase of SZ catalyst was pure mesoporous tetragonal ZrO2 with nano in size (5–10 nm). The increasing concentration of NH4OH solution enhanced the hydrolysis and condensation process, as confirmed by formation of additional Zr O Zr, Si O Si and Si O Zr bonds. The formation of oxygen vacancy (Vo) and Zr3+ surface defects (ZSD) also increased proportionally with the concentration of NH4OH solution. Both properties and the Si O Zr bond are supposed to play important roles in stabilizing the tetragonal phase of ZrO2. The Vo and ZSD also lowered the band-gap energy (from 4.35 eV to 3.05 eV) and act as electron acceptors. Catalytic testing showed that 8-SZ gave the highest initial rate (0.372× 10−3 mM min−1) of 10 mg L−1 BPA at pH 7 using 0.5 g L−1 catalyst within 4 h while under similar conditions, 5-SZ, 3-SZ, 0-SZ, ZrO2 and TiO2 only gave 0.263 × 10−3, 0.211 × 10−3, 0.145× 10−3, 0.026× 10−3 and 0.305 × 10−3 mM min−1, respectively. These results demonstrate that higher numbers of Si O Zr, Vo, and ZSD seemed to be the main factors in the high photoactivity of SZ prepared in 8 M NH4OH solution (8-SZ). A kinetic study demonstrated that the photodegradation followed the pseudo-first-order Langmuir-Hinshelwood model. The mechanism study using scavenging agents proved that photogenerated hole was the main active species, thus led more hydroxyl radicals formed to degrade the BPA. The 8-SZ also exhibited a great potential on degradation of various phenols and dyes in wastewater.

Nickel (Ni), cobalt (Co), and zinc (Zn) loaded on fibrous silica KCC-1 was investigated for CO2 methanation reactions. Ni/KCC-1 exhibits the highest catalyst performance with a CH4 formation rate of 33.02 × 10–2 molCH4 molmetal–1 s–1, 1.77 times higher than that of Co/KCC-1 followed by Zn/KCC-1 and finally the parent KCC-1. A pyrrole adsorption FTIR study reveals shifting of perturbed N–H stretching decreasing slightly with the addition of metal oxide, suggesting that the basic sites of catalyst were inaccessible due to metal oxide deposition. The strengths of basicity were found to follow sthe equence KCC-1, Ni/KCC-1, Zn/KCC-1, and Co/KCC-1. The data were supported by N2 adsorption desorption analysis, where Co/KCC-1 displayed the greatest reduction in total surface area whereas Ni/KCC-1 displayed the least reduction. The elucidation of difference mechanism pathways has also been studied by in situ IR spectroscopy studies to determine the role of different metal oxides in CO2 methanation. It was discover...

Amorphous TiO2 (AT) was successfully prepared via the sol-gel technique, using different titanium sources followed by incorporation of copper via the electrochemical method to give CuO/TiO2 (CAT) catalysts. The catalysts were characterized via XRD, N2 physisorption, FTIR, TEM, EDX, XPS, ESR and UV–Vis DRS. The results verified that the use of different titanium precursors have profound effect on the physicochemical properties of the AT catalysts. Further one-pot self-doping carbon from titanium precursor during the addition of copper could greatly enhanced the photocatalytic activity of CAT on the oxidative desulphurization of dibenzothiophene (DBT). 15 CATTBOT exhibited the best performance mainly due to the narrowest band gap and higher numbers of O–Ti–C and Ti–O–C bonds, as well as appropriate amount of Ti3+ surface defects (TSD). These abovementioned properties offered good mobility of electron-hole pairs and/or trap the electrons for enhancement of photoactivity under irradiation of visible light. Kinetic studies showed that the photocatalytic oxidative desulphurization of DBT followed the pseudo-first order Langmuir-Hinshelwood model, where the adsorption was the controlling step. It is believed that these results could contribute to the synthesis of various supported catalysts for numerous applications specifically in removal of sulphur containing compounds in fuel oils.

Copper oxide (CuO, 10–90 wt%) was loaded onto carbon nanotubes (CNTs) by electrosynthesis method. The catalysts (CuO/CNT) were characterized by XRD, nitrogen adsorption–desorption, ESR, FTIR, Raman, and XPS spectroscopy. The results indicated that a lower amount of CuO was dispersed well on the CNT, while higher loading was agglomerated, producing large-size crystallites, hence resulting in lower specific surface area. Adsorption studies revealed that the isotherms are fitted well with the Langmuir model. Moreover, the n value that was obtained from Freundlich model indicated that adsorption process is chemisorption. Photodegradation of p-chloroaniline (PCA) under visible light irradiation demonstrated that the 50 wt% CuO/CNT catalyst gave the highest degradation (97%). It was concluded that C N moieties of PCA were chemisorbed on the catalyst prior to photodegradation, while the Cu O C bonds, surface defects and oxygen vacancies were the main active site in enhancing the subsequent photodegradation. The kinetics of photodegradation were correlated with pseudo-first-order model, verifying the surface reaction was the controlling step. Remarkable mineralization results of PCA were attained by TOC (89.1%) and BOD5 (50.7%). It was also evidenced that the catalyst has a good potential toward degradation of various endocrine disruption compounds.

Despite its inherent constraints which hindered significant improvement in the process catalytically, the oxidative coupling of methane (OCM) remains an indispensable prospective approach for converting methane directly into vital chemicals such as ethylene. Recently, there is an upsurge in research effort towards better understanding of the oxidative coupling of methane process in terms of its mechanism, catalyst design and synthesis. This review discusses recent advances in crucial aspects related to the catalyst such as active sites, oxygen vacancy, acid–base property, surface oxide reducibility, oxide-support interaction, and prospects of nanowires with the aim to improve the performance of the OCM process.

Silica-doped tetragonal mesoporous zirconia nanoparticles, SiO2/ZrO2 (SZ), were successfully prepared by a simple microwave-assisted method, and the subsequent incorporation of copper (1–10 wt%) via an electrochemical method gave CuO/SiO2/ZrO2 (CSZ) catalysts. The SiO2 stabilized the ZrO2 completely in the tetragonal phase, but that the added copper occupied oxygen vacancies in the SZ lattice to perturb the catalysts and partially reintroduce the monoclinic phase. However, CuO enhanced the photoactivity of CSZ catalysts by lowering the band gap energy (from 4.35 eV to 2.70 eV) and acting as an electron trapper to suppress the recombination of electron–hole pairs. The activity of the catalysts in the photodegradation of bisphenol A was ranked in the following order: 5 CSZ (82%) > 1 CSZ (65%) > 10 CSZ (60%) > SZ (58%). The silica–copper–zirconia cooperative interactions affected the numbers of oxygen vacancies, defect sites, Zr–O–Si and Zr–O–Cu bonds, which consequently influenced the stabilization of ZrO2 as well as the photoactivity of each catalyst. A kinetic study demonstrated that the photodegradation followed the pseudo-first-order Langmuir–Hinshelwood model.

Side chain toluene methylation reaction (SCTM) is a reliable reaction to produce styrene and ethylbenzene from toluene. Nevertheless, due to the lack of efficient catalyst caused by less Lewis acid sites and mesoporosity properties, the challenges in this SCTM reaction are still ongoing. Hence, this work is accomplished to gain a better understanding in designing a robust catalyst for side chain toluene methylation. Herein, this work emphasizes the uniqueness of top-notch metal-free fibrous silica zeolite X (FZX) by microemulsion method. This FZX showed superior catalytic activity towards side chain methylation with 15.9% yield of styrene and ethylbenzene, which was 16-fold higher compared to the commercial zeolite X (CZX) catalyst. This was achieved by the excellent properties of dendrimeric silica fibers of FZX possessing high concentration of basic sites and Lewis acid sites as well as high mesoporosity, as proved by the FTIR-Pyrrole, FTR-Pyridine and nitrogen physisorption analyses respectively. The presence of intermediates was confirmed by in-situ FTIR toluene-methanol. 27Al MAS NMR analysis proved that the presence of excessive extraframework alumina (EFAl) species could act as additional Lewis acid sites in FZX to enhance toluene adsorption on the FZX catalyst, thus improving the toluene conversion and desired styrene and ethylbenzene products. Silica MCM41 exhibited lower yield of styrene and ethylbenzene by the fact imbalance of acid base property of catalyst. The kinetic study proved that the side chain toluene methylation occurred via dissimilar dual site mechanism of Langmuir-Hinshelwood. This rationally designed metal-free FZX demonstrates its high potential in polymer and/or petrochemical as well as other industrial applications.

Highly reactive visible-light-driven flower-like rutile-phase titanium nanoparticle (FTN) catalysts were prepared using a simple template-free hydrothermal method with different concentrations of hydrochloric acid (2 M–4M). The physicochemical properties of the catalysts were characterized via XRD, FESEM, FTIR, UV-DRS, N2 adsorption-desorption, and via ESR. Catalytic testing of the photodegradation of methylene blue (MB) was performed using 0.25 mg L−1 of catalyst for 90 min, which resulted in the following activity order: FTN-3M (98%) > FTN-4M (92%) > FTN-2M (86%). The remarkable photocatalytic performance shown by the FTN-3M catalyst was found to be due to its possession of the highest number of hydroxyl groups, oxygen vacancies, and titanium surface defects compared to other catalysts. The fastest reaction rate (4.49 × 10−2 min−1), which was achieved by the FTN-3M catalyst with values of kr = 0. 1845 mg L−1 min−1 and kLH = −0.1646 L mg−1. These values suggested that the reaction occurred on the surface of the catalyst, and was most probably influenced by the previously mentioned, three important properties. In addition, the open structure of the flower-like structure provided more accessible active sites for the adsorption of MB, as well as enhanced light harvesting through multiple reflections between the extended nanospindle structures. The degradation pathway for MB was also investigated. The FTN-3M catalyst maintained their activities for up to five runs without experiencing severe deactivation of the catalyst. Mineralization measurements for MB using TOC and BOD5 analyses, after 90 min of contact time, were 90.45% and 87.73%, respectively, using the FTN-3M sample. The cost-effectiveness of the FTN-3M catalyst proved that this photocatalytic process is greener and more sustainable than noun and should be implemented in industrial applications. It is expected that the extended light response range, in combination with the unique morphology of FTNs, could be exploited in the highly efficient treatment of wastewaters from the textile industry.

Spinel (Fe,Co,Ni)Al2O4 composites (FeCoNiAl) were prepared by an introduction of Ni, Co and Fe ions into a γ-Al2O3 framework via a simple electrochemical method. The physicochemical properties of the catalysts were studied by XRD, N2 adsorption-desorption, TEM, MP-AES, FTIR, XPS, ESR, and VSM analyses. The characterization data showed that an altered arrangement of the γ-Al2O3 framework was observed with a different structure, particularly with a formation of metal oxides and spinel phases as a consequence of dealumination, isomorphous substitution and surface oxygen defects that contributed to the magnetism properties. The adsorptivity toward Pd2+ was in the following order: FeCoNiAl > CoNiAl > NiAl. A strong coercive fields possessed by hercynite (FeAl2O4) in the FeCoNiAl was found to play an important role in the adsorption. The detailed adsorption equilibrium isotherms, kinetic, thermodynamics, and optimization were also studied to clarify the related results. The equilibrium data were fitted using the Langmuir model with 0.1 g L−1 FeCoNiAl giving the maximum monolayer adsorption capacity (qm) of 303 mg g−1 at 303 K and pH 5. The adsorption kinetics were best described by the pseudo-first-order model. Thermodynamic studies showed that the adsorption was exothermic and not spontaneous at high temperatures. Optimization by response surface methodology (RSM) with a central composite design (CCD) model supported this result by demonstrating that the reaction temperature played an important role in the adsorption.

Hydrogen is a zero-carbon footprint energy source with high energy density that could be the basis of future energy systems. Membrane-based water electrolysis is one means by which to produce high-purity and sustainable hydrogen. It is important that the scientific community focus on developing electrolytic hydrogen systems which match available energy sources. In this review, various types of water splitting technologies, and membrane selection for electrolyzers, are discussed. We highlight the basic principles, recent studies, and achievements in membrane-based electrolysis for hydrogen production. Previously, the Nafion™ membrane was the gold standard for PEM electrolyzers, but today, cheaper and more effective membranes are favored. In this paper, CuCl–HCl electrolysis and its operating parameters are summarized. Additionally, a summary is presented of hydrogen production by water splitting, including a discussion of the advantages, disadvantages, and efficiencies of the relevant technologies. Nonetheless, the development of cost-effective and efficient hydrogen production technologies requires a significant amount of study, especially in terms of optimizing the operation parameters affecting the hydrogen output. Therefore, herein we address the challenges, prospects, and future trends in this field of research, and make critical suggestions regarding the implementation of comprehensive membrane-based electrolytic systems.

The co-existence of heavy metals and organic compounds including Cr(VI) and p-cresol (pC) in water environment becoming a challenge in the treatment processes. Herein, the synchronous photocatalytic reduction of Cr(VI) and oxidation of pC by silver oxide decorated on fibrous silica zirconia (AgO/FSZr) was reported. In this study, the catalysts were successfully developed using microemulsion and electrochemical techniques with various AgO loading (1, 5 and 10 wt%) and presented as 1, 5 and 10-AgO/FSZr. Catalytic activity was tested towards simultaneous photoredox of hexavalent chromium and p-cresol (Cr(VI)/pC) and was ranked as followed: 5-AgO/FSZr (96/78%) > 10-AgO/FSZr (87/61%) > 1-AgO/FSZr (47/24%) > FSZr (34/20%). The highest photocatalytic activity of 5-AgO/FSZr was established due to the strong interaction between FSZr and AgO and the lowest band gap energy, which resulted in less electron-hole recombination and further enhanced the photoredox activity. Cr(VI) ions act as a bridge between the positive charge of catalyst and cationic pC in pH 1 solution which can improve the photocatalytic reduction and oxidation of Cr(VI) and pC, respectively. The scavenger experiments further confirmed that the photogenerated electrons (e−) act as the main species for Cr(VI) to be reduced to Cr(III) while holes (h+) and hydroxyl radicals are domain for photooxidation of pC. The 5-AgO/FSZr was stable after 5 cycles of reaction, suggesting its potential for removal of Cr(VI) and pC simultaneously in the chemical industries.

In this work, fibrous silica-titania (FST) was successfully prepared by the microemulsion method prior to the addition of three types of carbonaceous materials: graphitic-carbon nitride, g-C3N4 (CN), graphene nanoplatelets (GN), and multi-wall carbon nanotubes, MWCNT (CNT), via a solid-state microwave irradiation technique. The catalysts were characterized using XRD, FESEM, TEM, FTIR, UV-Vis DRS, N2 adsorption-desorption, XPS and ESR, while their photoactivity was examined on the degradation of toxic 2-chlorophenol (2-CP). The result demonstrated that the initial reaction rate was in the following order: CNFST (5.1 × 10–3 mM min-1) > GNFST (2.5 × 10–3 mM min-1) > CNTFST (2.3 × 10–3 mM min-1). The best performance was due to the polymeric structure of g-C3N4 with a good dispersion of C and N on the surface FST. This dispersion contributed towards an appropriate quantity of defect sites, as a consequence of the greater interaction between g-C3N4 and the FST support, that led to narrowed of band gap energy (2.98 eV to 2.10 eV). The effect of scavenger and ESR studies confirmed that the photodegradation over CNFST occurred via a Z-scheme mechanism. It is noteworthy that the addition of green carbonaceous materials on the FST markedly enhanced the photodegradation of toxic 2-CP.

Conversion of industrial pepper bio-waste (PW) to microcrystalline cellulose (MCC) was investigated as reinforcement agent of natural polymer bio-composites. The investigation highlighted the importance of hydrothermal assisted alkalization step for efficient separation of cellulose from lignin in PW in order to enhance the yield and the crystallinity of MCC. Cellulose was isolated from industrial pepper bio-waste via three steps i.e. alkalization, bleaching and hydrothermal assisted re-alkalization. Hydrothermal treatment during re-alkalization step increased the release of lignin that was bound within the cellulose domain via dissociation of the multiple bonds in the three-dimensional polymer and significantly reduced the lignin concentration. Optimization of hydrolysis parameters i.e. the concentration of HCl, the hydrolysis temperature and time, and also the solid/liquid ratios produced 86% of MCC with high crystallinity index ∼78.9%. The physicochemical properties of MCC isolated from PW exhibited a highly crystalline microcellulose structure with high thermal stability that were comparable to the physicochemical properties of the commercial MCC. Incorporation of MCC with seaweed and chitosan natural polymer showed the enhancement of the tensile strength and the elongation of the bio-composites, which exhibited the potential use of MCC as reinforcement agent in bio-composites to replace traditional plastic.

The effect of different pellet sizes of nickel (Ni) and lanthanum (La) promoted Al2O3 support on the catalytic performance for selective hydrogen production from polyethylene terephthalate (PET) plastic waste via steam reforming process has been investigated. The catalysts were prepared by impregnation method and were characterized using XRD, BET, TPD-CO2, TPR, SEM, EDX, TEM and TGA. The results showed that Ni La-co-impregnated Al2O3 catalyst has excellent activity for the production of hydrogen. Feed conversion of 88.53% was achieved over 10% Ni/Al2O3 catalyst which increased to 95.83% in the case of 10% Ni-5% La/Al2O3 catalysts with a H2 selectivity of 70.44%. The catalyst performance in term of gas production and feed conversion was further investigated under various operating parameters, e.g., feed flow-rate, and catalyst pellet size. It was found that at 0.4 ml/min feed flow rate, highest feed conversion and H2 selectivity were achieved. The Ni particles, which are the noble-based active species are highly effective, thus offered good hydrogen production in the phenol-PET steam reforming process. Incorporation of La as a promoter in Ni/Al2O3 catalyst has significantly increased the catalyst reusability with prolonged stability. The Ni La/Al2O3 catalyst with larger size showed remarkable activity due to the presence of significant temperature gradients inside the pellet compared to smaller size. Additionally, the catalyst showed only slight decrease in H2 selectivity and feed conversion even after 24 h, although production of carbon nanotubes was evidenced on its surface.

The effects of Cr 2 O 3 loading ranging from 1 to 12 wt.% on the properties, structure and isopropylbenzene (IPB), 1,4-diisopropylbenzene (DIPB) and 1,3,5-triisopropylbenzene (TIPB) hydrocracking activities of Pt/Cr 2 O 3 -ZrO 2 (Pt/CrZr) were studied. The properties of Pt/CrZr were characterized with XRD, BET, IR and UV–vis spectrometer. The acidity was determined by 2,6-lutidine adsorbed IR spectroscopy. The introduction of Cr 2 O 3 on ZrO 2 intensified continuously the tetragonal phase of ZrO 2 and bulk crystalline Cr 2 O 3 , while the surface area and acidity passed through a maximum of Cr 2 O 3 loading at 8 wt.%. The IR study confirmed the presence of Cr O stretching bands at 1035 and 1013 cm −1 on Pt/CrZr. No dioxo species involving the stretching modes of O Cr O existed. H 2 and 2,6-lutidine showed different interactions with Pt/CrZr in which the band at 1013 cm −1 is more extensively affected with 2,6-lutidine adsorption for all Pt/CrZr and the band at 1035 cm −1 is more affected with H 2 adsorption for Cr 2 O 3 loading at ≤ 8 wt.%. While, at > 8 wt.% Cr 2 O 3 loading, the H 2 is more interacted with the band at 1013 cm −1 . These results suggested that the absorbance bands at 1013 and 1035 cm −1 are assignable to the stretching of the Cr O which is connected to the other Cr through O and Cr O which is connected to cus Zr 4+ through O, respectively. The catalyst with 8 wt.% loading performed with a maximum activity in IPB, DIPB and TIPB hydrocracking at 523 K which may be due to presence of Cr O band at 1035 cm −1 which extensively interacted with H 2 to form protonic acid sites via a hydrogen spillover phenomenon. In fact, Cr 2 O 3 loading at 8 wt.% possessed strong permanent Lewis acid sites which play an important role in the stabilization of an electron during the formation of protonic acid sites.

In this study, the performance of mesoporous ZSM-5 has been studied on the esterification of acetic acid (AA) with benzyl alcohol (BA). The mesoporous ZSM-5 catalyst has been synthesized with the variation of aging time i.e. 6, 12, and 24 hours at the same temperature, 70 °C. The cation exchange of Na-ZSM-5 to H-ZSM-5 was performed before the catalytic activity test. The acidity type and amount of solids were determined by FT-IR spectroscopy using pyridine as a probe molecule. The characterization by pyridine adsorption showed that at a higher mesoporous surface area, the number of Lewis acid was increased. The highest mesoporous surface area, Lewis, and Bronsted acid sites were obtained by sample which has the lowest crystallinity, i.e. 255.78 m 2 /g, 0.2732 mmol/g, and 0.20612 mmol/g, respectively. Influence of mesoporous volume was studied on the catalytic activity of the mesoporous ZSM-5 in the esterification reaction. Conversion of acetic acid in the esterification reaction for samples of HZ-6, HZ-12, and HZ-24 were obtained by titration methods, i.e. 39.59, 36.39, and 32.90 %, respectively. Hence, the reaction temperature of 393 K, molar ratio 1:4 (AA:BA) and catalyst loading 5 % were selected as an optimum reaction parameters. Copyright © 2017 BCREC Group. All rights reserved Received: 21 st November 2016; Revised: 1 st February 2017; Accepted: 18 th February 2017 How to Cite : Kusumaningtyas, D.T., Prasetyoko, D., Suprapto, Triwahyono, S., Jalil, A.A., Rosidah, A. (2017). Esterification of Benzyl Alcohol with Acetic Acid over Mesoporous H-ZSM-5. Bulletin of Chemical Reaction Engineering & Catalysis , 12 (2): 243-250 (doi:10.9767/bcrec.12.2.806.243-250) Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.806.243-250

Nickel (Ni)-cobalt (Co) supported on lanthanum (III) oxide (La2O3) catalyst was prepared via impregnation technique to study the steam reformation of acetic acid for hydrogen generation by using one-step fixed bed reactor. Moreover, in order to specify the physical and the chemical attributes of the catalyst, X-ray diffraction (XRD), nitrogen physisorption, temperature-programmed reduction (TPR), temperature-programmed desorption of ammonia and carbon dioxide (TPD-NH3 and CO2), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) methods were employed. The nitrogen physisorption analysis showed that the presence of Co on Ni/La2O3 improved the textural properties of the catalyst by increasing the surface area, the pore diameter and the pore volume of the catalyst. This improved the dispersion of metal particle and caused a reduction in the size of metal particle, and consequently, increased the catalytic activity, as well as the resistance to coke formation. On top of that, the condensation and the dehydration reactions during acetic acid steam reforming created carbon deposition on acidic site of the catalyst, which resulted in the deactivation of catalyst and the formation of coke. Besides, in this study, Ni/La2O3 contributed to a high acetic acid conversion (100%) at 700 °C, but it produced more coking compared to Ni–Co/La2O3 and Co/La2O3 catalysts.

Molybdenum oxide (MoO3) supported on bicontinuous concentric lamellar silica KCC-1 (MoO3/KCC-1) and phosphorus (P) loaded on MoO3/KCC-1 (P/MoO3/KCC-1) were successfully prepared by physical mixing of MoO3 followed by impregnation of phosphoric acid. The physicochemical properties of the catalysts were characterized by XRD, FESEM, N2 physisorption, 29Si NMR, FTIR and n-heptane isomerization. In the presence of hydrogen, KCC-1, MoO3/KCC-1 and P/MoO3/KCC-1 showed n-heptane rate conversion of 0.02 × 10−8 mol/m2 s, 0.94 × 10−8 mol/m2 s and 4.79 × 10−8 mol/m2 s, respectively at 300 °C. The presence of MoO3 and phosphorus enhanced the rate conversion of n-heptane due to the formation of (MoOx)-(Hy)+ and the participation of acidic centers from the presence of phosphorus in the formation of protons by trapping electrons, respectively. Additionally, the unique morphology of silica KCC-1 also contributed to the high catalytic activity, by allowing high accessibility of bulky mass reactant to the active sites. The analysis of variance (ANOVA) indicated that the reaction temperature was the prominent significant variable in the production of isomers, followed by treatment temperature and treatment time. The optimum yield of isomers predicted from the response surface analysis is 44.9% at reaction temperature of 311 °C, treatment temperature of 464 °C and treatment time of 6 h.

Mesoporous silica KCC-1 was successfully synthesized by microemulsion system coupled with microwave-assisted hydrothermal method. Mesoporous silica KCC-1 exhibited spherical morphology surrounded with dendritic fiber with the particle size of 200–400 nm and BET surface area of 773 m2/g. Mesoporous silica KCC-1 has significantly higher number of basicity and oxygen vacancy than those of MCM-41 and SiO2 which directly correlated with the catalytic performance of the catalyst. The activity of mesoporous silica KCC-1 in CO2 methanation is five-fold higher than MCM-41 with the yield of CH4 reached 38.9% at 723 K.