Development of fibrous mesoporous silica for catalytic reaction : A short review

The activity of the catalyst is markedly influenced by the physical and chemical properties of the support materials. Designing and developing excellent features of support materials is a crucial approach since it could directly affect the quality of metal active sites dispersion, strength of metal-support interaction, and quantity of oxygen vacancies, thus improving the catalytic performance and stability. Several modifications on support synthesis have been reported and the alteration into fibrous mesoporous silica material has attracted considerable attention over the recent years. Thus, the latest development of fibrous mesoporous silica for catalytic reaction has been reviewed through this work. Additionally, the governing factors of fibrous mesoporous silica in catalytic reaction was discussed in this review article

Promising hydrothermal technique for efficient CO2 methanation over Ni/SBA-15

The comparative study of different hydrothermal treatment techniques (Reflux (R) and Teflon (T)) and without hydrothermal technique (W) towards efficient CO2 methanation over Ni/SBA-15 was discussed. X-ray diffraction (XRD), inductive coupling plasma-atomic emission spectroscopy (ICP-AES), N2 adsorption-desorption isotherms (BET), Fourier transform infrared (FTIR) spectroscopy, UV-vis diffuse reflectance spectroscopy (UV-Vis DRS), scanning electron microscope – energy dispersion x-ray (SEM-EDX), and transmission electron microscope (TEM) analysis showed that Ni/SBA-15(R) possessed fascinating catalytic properties owing to the highest surface area (814 m2/g) and pore diameter (5.49 nm) of SBA-15(R), finest metal particles (17.92 nm), strongest metal-support interaction and highest concentration of basic sites. The efficacy of Ni/SBA-15 towards CO2 methanation was descending as Ni/SBA-15(R) > Ni/SBA-15(T) > Ni/SBA-15(W), implying the outstanding performance of Ni/SBA-15(R) which in parallel with the characterization results. The lowest performance of Ni/SBA-15(W) was due to the poorest properties of support; lowest surface area and pore diameter, largest Ni sizes, weakest metal-support interaction and lowest concentration of basic sites. This study successfully developed fascinating Ni/SBA-15 through the reflux hydrothermal treatment technique for CO2 methanation

Tailoring the Properties and Catalytic Activities of Ni/SBA-15 via Different TEOS/P123 Mass Ratios for CO2 Reforming of CH4

The influences of tetraethylorthosilicate/ triblockcopolymer (TEOS/P123) mass ratios on the properties and catalytic activity of Ni/SBA-15 towards CO2 reforming of CH4 were studied. A series of samples with different mass ratios of TEOS/P123 (1.5, 2.21 and 3.0) were prepared and characterized by XRD, BET, SEM, TEM, FTIR and UV–vis DRS. The characterization results clearly indicated that TEOS/P123 mass ratio of 2.21 was the optimal synthesis ratio of Ni/SBA-15 which produces the well-ordered hexagonal mesoporous structure with the highest Ni-support interaction. The catalytically favorable textural properties of Ni/SBA-15(R2.21) enhanced the dispersion of metal particles, improved the catalyst activity, increased the catalyst stability and reduced the carbon deposition. The conversion of CH4 and CO2 over Ni/SBA-15(R2.21) were about 89% and 88%, respectively and H2/CO ratio of 1.02. This study provides new perspectives on the Ni-based catalyst, particularly on the influence of TEOS/P123 mass ratio on the properties and catalytic activity of Ni/SBA-15 towards CO2 reforming of CH4

Adsorption of Pb(II) onto KCC-1 from aqueous solution: Isotherm and kinetic study

In this study, the removal of Pb(II) from aqueous solution using KCC-1 was investigated. BET and TEM revealed the favourable structure of KCC-1 which consists of fibrous morphology and high surface area. Batch adsorption experiment were performed to study the effect of contact time (40 – 160 min), effect of adsorbent dosage (0.5 – 5g/L), effect of initial concentration (50 – 400 mg/L) and effect of pH (2 – 8). The optimum condition was achieved at contact time of 80 min, adsorbent dosage of 4 g/L, initial concentration of 200 mg/L and pH of 6, with maximum removal of Pb(II) was 80.5%. The experimental data were analysed using Langmuir (Type 1, Type 2, Type 3 and Type 4), Freundlich, Temkin, and DubininRedushkevich isotherm models, and were found to follow Langmuir isotherm model with maximum adsorption capacity of 38.76 mg/g and high correlation coefficient (R2= 0.99), implying that the ongoing process is homogeneous in nature. Pseudo-first order, Pseudosecond order, Intra-particle diffusion and Elovich kinetic models were tested with the experimental data, and Pseudo-second order kinetic model was the best for the adsorption of Pb(II) onto KCC-1, indicating that the adsorption process most likely controlled by the chemisorption process and the rate of reaction is directly proportional to the number of active sites on the surface of adsorbent. The results obtained from this study revealed that KCC-1 had high potential for the adsorption of Pb(II) from aqueous solution

Enhanced Catalytic Performance Of Ni/Sba-15 Towards Co2 Methanation Via P123-Assisted Method

This study focused on the enhancement of catalytic performance of Ni/SBA-15 towards CO2 methanation via P123(PEG-PPG-PEG triblock copolymer)-assisted impregnation method. The pysical and chemical properties of the catalysts were characterized using XRD, BET and FTIR, meanwhile the catalytic performance of catalysts towards CO2 methanation were evaluated using stainless steel fixed bed reactor. The presence of coke on the surface of catalysts was characterized using TGA analysis. XRD and BET results revealed that the dispersion of Ni particles on the surface of SBA-15 were improved with P123 (Ni/SBA-15(P123)) as compared to without P123 (Ni/SBA-15). FTIR analysis revealed that P123 enhanced the formation of metal-support interaction (Si-O-Ni) through the substitution of O‒H with O‒Ni. Ni/SBA-15(P123) exhibited higher activity, better stability and less carbon formation owing to its smaller metal particles, stronger metal-support interaction and more homogenous metal dispersion, which altered the properties of catalyst towards an excellent catalytic performance. This study provides new perspective on the beneficial effect of P123- assisted impregnation method in the enhancement of catalytic performance of Ni/SBA-15 towards CO2 methanation

Hydrogen production via CO2 reforming of CH4 over low-cost Ni/SBA-15 from silica-rich palm oil fuel ash (POFA) waste

H2 was produced via CO2 reforming of CH4 (CRM) using low-cost Ni/SBA-15 synthesized from palm oil fuel ash (POFA) waste as silica precursor. A series of Ni/SBA-15 were synthesized by employing different Na2SiO3-POFA/P123 mass ratios (2.0, 2.9 and 4.0) and were compared with Ni/SBA-15 prepared from commercial Na2SiO3 (Ni/SBA-15(Comm.)). Na2SiO3-POFA/P123 = 2.9 was found to be the optimal synthesis ratio, which produces a well-defined hexagonal framework, smaller NiO particles, stronger Ni-support interaction, homogeneous metal distribution and higher amount of basic sites. The catalytic performance complied with the trend of Ni/SBA-15(R4.0) < Ni/SBA-15(R2.0) < Ni/SBA-15(R2.9) ≈ Ni/SBA-15(Comm.), indicating the excellent catalytic activity of Ni/SBA-15(R2.9) (H2 selectivity = 87.6%). The favorable physicochemical properties of Ni/SBA-15(R2.9) ameliorated the active Ni metals stabilization over SBA-15 and boosted the catalyst's virtues towards an outstanding catalytic performance. Hence, it is affirmed that POFA with an optimal Na2SiO3-POFA/P123 ratio of 2.9 can be served as silica substitution of Ni/SBA-15 for efficient H2 production via CRM

Facile synthesis of tunable dendritic fibrous SBA-15 (DFSBA-15) with radial wrinkle structure

In this study, typical mesoporous hexagonal rod-typed SBA-15 was successfully transformed into spherical shape with additional dendrimers, namely Dendritic Fibrous SBA-15 (DFSBA-15) by employing microwave-assisted microemulsion system. Physiochemical properties of DFSBA-15 were greatly influenced by aging temperature, urea/TEOS ratio, co-surfactant types, and aging time. It was found that the co-surfactant types were insignificant in controlling the pore size, while the aging conditions (temperature and time) were significant in controlling the fiber density. The analysis results (XRD, N2 physisorption, FTIR, and TEM) confirmed the optimal conditions for DFSBA-15 synthesis were at aging temperature of 100 °C, urea/TEOS ratio of 0.5, n-butanol as co-surfactant, and aging time of 12 h. The as-synthesized optimized DFSBA-15 was compared with the conventional SBA-15 via XRD, N2 physisorption, FTIR, CO2-TPD, NH3-TPD, TGA, TEM, and FESEM-EDX. As compared, DFSBA-15 rendered vast accessibility to the adsorption sites, higher basicity (≈86% enhancement) and acidity (≈66% enhancement), abundant siliceous framework and higher thermal stability (≈19% enhancement), owing to its radially oriented pores which elongated to the outer surface from the nucleus of its sphere. The outcome of this study anticipated the wide applications of DFSBA-15 in catalysis and biomedical fields by revealing the facile protocols of optimal DFSBA-15 synthesis

Methane dry reforming over Ni/fibrous SBA-15 catalysts: Effects of support morphology (rod-liked F-SBA-15 and dendritic DFSBA-15)

Santa Barbara Amorphous-15 (SBA-15) is a promising molecular sieve material with its highly uniform porosity; nonetheless, its tubular pore channels discouraged mass transfer of reactants during catalysis. Herein, SBA-15 was altered by microemulsion technique to prepare two fibrous SBA-15 with distinct morphologies, viz. rod-liked F-SBA-15 and dendritic DFSBA-15. After Ni impregnation, the Ni/fibrous SBA-15 catalysts (Ni/F-SBA-15 and Ni/DFSBA-15) were catalytically evaluated with methane dry reforming (MDR). From characterization, rod-shaped F-SBA-15 had outer fibrous layer whereas dendritic DFSBA-15 consisted of a solid core with radially projected fibres. Besides, Ni/F-SBA-15 possessed uneven sized NiO but Ni/DFSBA-15 had uniform NiO dispersion. Characterization also proved that fibrillation and Ni impregnation did not alter the pristine properties of SBA-15. However, the surface attributes of SBA-15 remarkably reduced after fibrillation and Ni impregnation. The strength of metal-support (Ni-SiO2) interaction could be ranked as: Ni/DFSBA-15 > Ni/F-SBA-15 > Ni/SBA-15 (previously reported). Both Ni/fibrous SBA-15 catalysts exhibited high proportion of moderate basicity, which favoured the carbon removal via reverse Boudouard reaction. In accordance with endothermicity, the optimal temperature of MDR over both catalysts was 800 °C as greater temperature provoked conspicuous CH4 thermal decomposition. For 50 h MDR at 800 °C, both catalysts presented superior catalytic activity and stability. With a fully accessible siliceous framework, Ni/DFSBA-15 attained greater reactant conversions (84.05–87.40% XCH and 81.80–85.60% XCO) than Ni/F-SBA-15 (80.30–85.80% XCH and 76.73–84.10% XCO). In overall, Ni/DFSBA-15 was more coke-resistant than Ni/F-SBA-15 by virtue of its fully accessible structure, uniformly dispersed Ni phase, and stronger metal-support interaction

Methane dry reforming over Ni/fibrous SBA-15 catalysts: Effects of support morphology (rod-liked F-SBA-15 and dendritic DFSBA-15)

Santa Barbara Amorphous-15 (SBA-15) is a promising molecular sieve material with its highly uniform porosity; nonetheless, its tubular pore channels discouraged mass transfer of reactants during catalysis. Herein, SBA-15 was altered by microemulsion technique to prepare two fibrous SBA-15 with distinct morphologies, viz. rod-liked F-SBA-15 and dendritic DFSBA-15. After Ni impregnation, the Ni/fibrous SBA-15 catalysts (Ni/F-SBA-15 and Ni/DFSBA-15) were catalytically evaluated with methane dry reforming (MDR). From characterization, rod-shaped F-SBA-15 had outer fibrous layer whereas dendritic DFSBA-15 consisted of a solid core with radially projected fibres. Besides, Ni/F-SBA-15 possessed uneven sized NiO but Ni/DFSBA-15 had uniform NiO dispersion. Characterization also proved that fibrillation and Ni impregnation did not alter the pristine properties of SBA-15. However, the surface attributes of SBA-15 remarkably reduced after fibrillation and Ni impregnation. The strength of metal-support (Ni-SiO2) interaction could be ranked as: Ni/DFSBA-15 > Ni/F-SBA-15 > Ni/SBA-15 (previously reported). Both Ni/fibrous SBA-15 catalysts exhibited high proportion of moderate basicity, which favoured the carbon removal via reverse Boudouard reaction. In accordance with endothermicity, the optimal temperature of MDR over both catalysts was 800 °C as greater temperature provoked conspicuous CH4 thermal decomposition. For 50 h MDR at 800 °C, both catalysts presented superior catalytic activity and stability. With a fully accessible siliceous framework, Ni/DFSBA-15 attained greater reactant conversions (84.05–87.40% and 81.80–85.60% ) than Ni/F-SBA-15 (80.30–85.80% and 76.73–84.10% ). In overall, Ni/DFSBA-15 was more coke-resistant than Ni/F-SBA-15 by virtue of its fully accessible structure, uniformly dispersed Ni phase, and stronger metal-support interactio

Ni/Fibrous type SBA-15: Highly active and coke resistant catalyst for CO2 methanation

The rod-like SBA-15 was transformed into fibrous type SBA-15 (F-SBA-15). The Ni/F-SBA-15 was catalytically evaluated in CO2 methanation and compared with conventional Ni/SBA-15. A superior catalytic performance was shown by Ni/F-SBA-15 (CO2 conversion = 99.7%, and CH4 yield = 98.2%) than Ni/SBA-15 (CO2 conversion = 91.1%, and CH4 yield = 87.5%). This phenomenon was attributed to the favorable physicochemical properties of F-SBA-15 as evidenced by the characterization results. A higher homogeneity of finer Ni was embedded onto the F-SBA-15 support, subsequently strengthened the Ni interaction with F-SBA-15, and increased the amount of moderate basic sites. The in situ FTIR studies evidenced the CO2 methanation over both catalysts proceeded via CO2 dissociation pathway. Three intermediate species (linear carbonyl, unidentate, and bidentate carbonates) were detected for Ni/F-SBA-15, while only bidentate carbonates were detected for Ni/SBA-15, signifying excellent catalytic attributes of Ni/F-SBA-15. Additionally, Ni/F-SBA-15 demonstrated higher stability and coke resistance ability than Ni/SBA-15