Understanding porous structure of SBA-15 upon pseudomorphic transformation into MCM-41: Non-direct investigation by carbon replication

Rafał Janus,Mariusz Wa˛drzyk,Marek Lewandowski,Piotr Natka nski,Piotr Ła˛tka,Piotr Ku strowski 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-

A series of mesoporous silicas with bimodal porosity combining the features of broad-mesoporousSBA-15 and narrow-mesoporous MCM-41 was synthesized by the pseudomorphic transformation ofSBA-15. The pore size of the MCM-41-like fraction was adjusted using different quaternary ammoniumsalts, while the degree of pseudomorphic transformation was tuned by the alkalinity of the mother-silicadissolving agent. The produced silicas were applied as hard templates for the synthesis of carbon replicasby nanocasting. The mechanism of pseudomorphic transformation of mesoporous silica was for thefirsttime investigated non-directly, employing the strategy of inverse carbon nanoreplication followed bycomprehensive study of the textural and structural parameters of replicas with regard to silica matrices. It was found that the conversion of SBA-15 into MCM-41 occurs simultaneously throughout the entireparticle’s body according to the mechanism of homogeneous pseudomorphic transformation. It wasevidenced that the strategy of inverse carbon replication could be successfully employed as an ingenioustool for non-direct investigation of suchlike silica transformations towards hierarchical porous systems. Furthermore, the unique bimodal mesoporosity of the carbons obtained from SBA-15 partiallytransformed into MCM-41 opens a possibility for their application in a variety of purposes, mainly incatalysis and adsorption.

Synthesis of high-performance Ni/Ce0.8Zr0.2O2 catalyst via co-nanocasting method for ethanol dry reforming

Guangyu Shi,Yuanhao Wang,Yafeng Cao,Weijie Cai,Fengzhi Tan 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.12

A Ni/Ce0.8Zr0.2O2 catalyst (NiCeZr-N) was synthesized by a facile co-nanocasting technique for syngas production from ethanol dry reforming. In addition, a series of characterization techniques, such as transmission electron microscopy (TEM), X-ray diffraction (XRD), inductive coupled plasma Emission Spectrometer (ICP), X-ray photoelectron spectroscopy (XPS), Raman and hydrogen temperature programmed reduction (H2-TPR) were selected to evaluate the physicochemical features of the as-prepared catalysts. Indeed, the results indicated that NiCeZr-N catalyst prepared by co-nanocasting method had a smaller particle size (<5 nm), relatively higher specific surface area (39m2/g) and stronger metal-support interaction in comparison with another model catalyst obtained from conventional co-precipitation method (NiCeZr-P). Expectedly, these positive factors enabled NiCeZr-N catalyst to exhibit better activity and stability. Typically, ethanol is completely converted by using NiCeZr-N as catalyst and heating to 700 oC, and CO2 conversion was as high as 65.3%. Interestingly, H2/CO was close to 1.1 at 650 oC, which could be used as feedstocks of Fischer-Tropsch process. Particularly, no obvious fluctuation of ethanol conversion and the product selectivity was observed during 40 h time-on-stream stability test.

Preparation of highly ordered mesoporous In₂O₃ and its application for CO₂ hydrogenation

곽태열,배종욱 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Nanocasting method is one of the significant ways to synthesize highly ordered mesoporous metal oxides such as indium oxides having hexagonal or cubic mesoporous structures. Indium oxides can be utilized for methanol synthesis by CO₂ hydrogenation at a relatively higher temperature with a higher selectivity to methanol and stability. In the present study, the highly ordered mesoporous indium oxides were successfully synthesized and tested for CO₂ hydrogenation to methanol at the reaction condition of T = 300 oC, P = 5.0 MPa, and the ordered mesoporous indium oxides showed a different catalytic activity according to its crystalline structures such as hexagonal or cubic structures as well as the mesoporous porosity.

CO2 adsorption on oxygen enriched nanostructured carbons derived from silica templated resorcinol-formaldehyde

Deepak Tiwari,Simarjot Kaur,Haripada Bhunia,Pramod K. Bajpai 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.65 No.-

Carbon dioxide capture needs development of cost effective CO2 capture technologies. This paper describes oxygen enriched nanostructured carbons synthesized from nanocasting technique using mesoporous silica as template and resorcinol-formaldehyde as precursor. Carbonization at various temperatures (600 °C–800 °C) was carried out to develop range of carbon adsorbents. Thorough characterization of textural, surface and chemical properties was carried out on prepared carbons and evaluated for CO2 capture performance using thermogravimetric analyser under dynamic conditions. Highest dynamic CO2 uptake capacity was reported to be 1.5 mmol g−1 by SRF-700 at 30 °C in 100% pure CO2. The CO2 uptake performance of the prepared carbons is affected by both the textural properties and surface chemistry. Four adsorption–desorption cycles established the material with complete stability and regenerability. Fractional order kinetic model completely described CO2 adsorption on prepared carbons. Thermodynamic parameter values suggested spontaneous, random and exothermic nature of the process. Energetically heterogeneous surface of adsorbent was confirmed by best fitting of Temkin isotherm and random pattern of isosteric heat of adsorption with surface coverage. Approximately, 1.82 MJ per kg CO2 thermal energy is required for desorption process.

Aluminium Salt of Phosphomolybdic Acid Fabricated by Nanocasting Strategy: An Efficient System for Selective Oxidation of Benzyl Alcohols

Aliyan, Hamid,Fazaeli, Razieh,Habibollahi, Nasibeh Korean Chemical Society 2012 대한화학회지 Vol.56 No.5

Preparation of $AlPMo_{12}O_{40}$ (AlPMo) salts, supported on mesostructured SBA-15 silica, by the reaction deposition strategy causes the formation of isolated AlPMo nanocrystals inside the nanotubular channels. The remarkable characteristic of the SBA-15 structure is that all the cylindrical pores are connected by some small channels. This makes the whole pore system in SBA-15 three-dimensional. We have used 2D hexagonal SBA-15 silicas as hard templates for the nanofabrication of AlPMo salt nanocrystal. The oxidation of alcohols occurs effectively and selectively with $H_2O_2$ as the oxidant. AlPMo salt nanocrystal was used as the catalyst.

1P-482 Cerium-metal oxides prepared by nanocasting synthesis for CO oxidation

이성빈,이정호,박진서,이정화,이정양,김범년,김지만 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

Combustion of fossil fuels in power plants, motor vehicles, and other incineration processes emits different toxic pollutants (CO, NO_x, SO₂ etc), which are very dangerous to the environment. Particularly, the emission of carbon monoxide poses serious threat to human health as well as global climate change. Thus, the mitigation of CO emission is a paramount interest with the increasing demands of environmental protection. In this work, a series of mesoporous ceria based binary metal oxide catalysts prepared by nano-replication method was evaluated in the CO oxidation reaction. The structure of the catalysts were characterized using powder X-ray diffraction (XRD), nitrogen adsorption & desorption isotherms, Raman spectrums, scanning electron microscopy (SEM), temperature programmed study experiments.

Highly Ordered Mesoporous Crystalline MoSe₂ Material with Efficient Visible‐Light‐Driven Photocatalytic Activity and Enhanced Lithium Storage Performance

Shi, Yifeng,Hua, Chunxiu,Li, Bin,Fang, Xiangpeng,Yao, Chaohua,Zhang, Yichi,Hu, Yong‐,Sheng,Wang, Zhaoxiang,Chen, Liquan,Zhao, Dongyuan,Stucky, Galen D. WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.14

<P><B>Abstract</B></P><P>Highly ordered mesoporous crystalline MoSe<SUB>2</SUB> is synthesized using mesoporous silica SBA‐15 as a hard template via a nanocasting strategy. Selenium powder and phosphomolybdic acid (H<SUB>3</SUB>PMo<SUB>12</SUB>O<SUB>40</SUB>) are used as Se and Mo sources, respectively. The obtained products have a highly ordered hexagonal mesostructure and a rod‐like particle morphology, analogous to the mother template SBA‐15. The UV‐vis‐NIR spectrum of the material shows a strong light absorption throughout the entire visible wavelength region. The direct bandgap is estimated to be 1.37 eV. The high surface area MoSe<SUB>2</SUB> mesostructure shows remarkable photocatalytic activity for the degradation of rhodamine B, a model organic dye, in aqueous solution under visible light irradiation. In addition, the synthesized mesoporous MoSe<SUB>2</SUB> possess a reversible lithium storage capacity of 630 mAh g<SUP>−1</SUP> for at least 35 cycles without any notable decrease. The rate performance of mesoporous MoSe<SUB>2</SUB> is much better than that of analogously synthesized mesoporous MoS<SUB>2</SUB>, making it a promising anode for the lithium ion battery.</P>

Non-siliceous ordered mesoporous materials via nanocastingfor small molecule conversion electrocatalysis

Du San Baek,Sang Hoon Joo 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.10

Since the pioneering work of Ryoo and co-workers in 1999 on the synthesis ofordered mesoporous carbons via nanocasting, the nanocasting pathway hasendured the test of time and has established itself as a robust and versatilemethod for preparing ordered mesoporous materials (OMMs). This methodenables the generation of a remarkably wide range of non-siliceous OMMs,some of which are otherwise inaccessible. In this account, we present ourdecade-long efforts toward the function-oriented design of non-siliceousOMM-based electrocatalysts for promoting small molecule conversion reac-tions relevant to renewable energy conversion and commodity chemical pro-duction, including hydrogen evolution reaction, oxygen evolution reaction, andselective oxygen reduction reaction. We also discuss the extension of the nano-casting concept to a silica-coating-mediated synthesis for preparing new cata-lytic materials. We conclude the account by suggesting the remainingchallenges and outlook for the future development of advanced OMMs.

Metal-Doped In2O3 Nanosphere Arrays with Enhanced Gas-Sensing Property

Xuanji Zhang,Ni Deng,Xianjia Chen,Yanting Yang,Jing Li,BO HONG,DINGFENG JIN,Xiaoling Peng,XINQING WANG,Hongliang Ge,HONGXIAO JIN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.3

In2O3 and metal-doped (Ni or Ce) In2O3 mesoporous three-dimensional (3D) nanospheres arrays were synthesized via nanocasting using mesoporous silica as hard templates. Effects of Ni or Ce doping on the structure, optical and gas-sensing properties of the In2O3 nanospheres were investigated. Both the undoped and the doped In2O3 nanospheres showed single-phase structure without any impurity. The nanospheres were about 20 nm in size and they stacked closely to formrigid 3D mesoporous structure. Achange in the value of optical band gap was observed upon metal doping. The room temperature photo luminescence behavior also showed some differences between pure and doped In2O3. Compared with pure In2O3 nanospheres, the metal-doped In2O3 exhibited superior response, fast recovery and good selectivity to ethanol. The enhanced gas-sensing properties might be related to the doping of metal ion and its effective contribution towards the oxygen vacancies, conductivity and crystallite size of the grains.

CO2 adsorption on oxygen enriched porous carbon monoliths: Kinetics, isotherm and thermodynamic studies

Jasminder Singh,Haripada Bhunia,Soumen Basu 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.60 No.-

The present study reports the use of nanocasted carbon monoliths (CMs) as adsorbents synthesized by using furfuryl alcohol as carbon precursor and silica monoliths (SM) as a template for CO2 capture. The oxygen content decreases from 18.92 to 14.38% with increase of carbonization temperature from 550 to 950 °C. BET surface area and total pore volume of CM carbonized at 950 °C was found to be maximum i.e. 1225 m2 g−1 and 1.26 cm3 g−1, respectively with the presence of a large number of micropores and mesopores. Performance evolution of the CMs was done thermogravimetrically at different adsorption temperatures and CO2 concentrations and found that, CM-950 shows the highest CO2 capacity (1.6 mmol g−1) which is approximately three times higher than SM (0.52 mmol g−1). The CMs exhibit stable CO2 uptake capacities (≥1 mmol g−1) with easy regenerability over multiple adsorption–desorption cycles. Furthermore, fractional order kinetic model provided the best description over all adsorption temperatures and CO2 concentrations. Heterogeneous nature of the carbon surface was confirmed from the Temkin isotherm fit and isosteric heat of adsorption (Qst) values.