Synergism Between Mo/Ni and Acidic Sites on NiMoS/ZSM-5 for Heavy Aromatic Hydrodealkylation

Niobium containing SBA-15 was prepared by two methods: impregnation with different amounts of ammonium niobate(V) oxalate (Nb-15/SBA-15 and Nb-25/SBA-15 containing 15 wt.% and 25 wt.% of Nb, respectively) and mixing of mesoporous silica with Nb2O5 followed by heating at 500 °C (Nb2O5/SBA-15). The use of these two procedures allowed obtaining materials with different textural/surface properties determined by N2 adsorption/desorption isotherms, XRD, UV-Vis, pyridine, and NO adsorption combined with FTIR spectroscopy. Nb2O5/SBA-15 contained exclusively crystalline Nb2O5 on the SBA-15 surface, whereas the materials prepared by impregnation had both metal oxide and niobium incorporated into the silica matrix. The niobium species localized in silica framework generated Brønsted (BAS) and Lewis (LAS) acid sites. The inclusion of niobium into SBA-15 skeleton was crucial for the achievement of high catalytic performance. The strongest BAS were on Nb-25/SBA-15, whereas the highest concentration of BAS and LAS was on Nb-15/SBA-15 surface. Nb2O5/SBA-15 material possessed only weak LAS and BAS. The presence of the strongest BAS (Nb-25/SBA-15) resulted in the highest dehydration activity, whereas a high concentration of BAS was unfavorable. Silylation of niobium catalysts prepared by impregnation reduced the number of acidic sites and significantly increased acrolein yield and selectivity (from ca. 43% selectivity for Nb-25/SBA-15 to ca. 61% for silylated sample). This was accompanied by a considerable decrease in coke formation (from 47% selectivity for Nb-25/SBA-15 to 27% for silylated material).

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Tailoring of Surface Acidic Sites in Co–MoS2 Catalysts for Hydrodeoxygenation Reaction

The Journal of Physical Chemistry Letters ◽

10.1021/acs.jpclett.1c01201 ◽

2021 ◽

pp. 5668-5674

Author(s):

Yijin Zhang ◽

Tangkang Liu ◽

Qineng Xia ◽

Hongyan Jia ◽

Xinlin Hong ◽

...

Keyword(s):

Acidic Sites ◽

Mos2 Catalysts

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Hydrogenation of Aromatic Hydrocarbons over Supported Pt Catalysts .III. Reaction Models for Metal Surfaces and Acidic Sites on Oxide Supports

Journal of Catalysis ◽

10.1006/jcat.1993.1299 ◽

1993 ◽

Vol 143 (2) ◽

pp. 563-572 ◽

Cited By ~ 124

Author(s):

S.D. Lin ◽

M.A. Vannice

Keyword(s):

Aromatic Hydrocarbons ◽

Metal Surfaces ◽

Pt Catalysts ◽

Oxide Supports ◽

Supported Pt Catalysts ◽

Hydrogenation Of Aromatic Hydrocarbons ◽

Reaction Models ◽

Acidic Sites

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Steam Reforming of Chloroform-Ethyl Acetate Mixture to Syngas over Ni-Cu Based Catalysts

Catalysts ◽

10.3390/catal11070826 ◽

2021 ◽

Vol 11 (7) ◽

pp. 826

Author(s):

Qiong Wu ◽

Chenghua Xu ◽

Yuhao Zheng ◽

Jie Liu ◽

Zhiyong Deng ◽

...

Keyword(s):

Ethyl Acetate ◽

Steam Reforming ◽

Synergetic Effect ◽

Mixed Oxide Catalysts ◽

Reforming Catalysts ◽

Acidic Sites ◽

Chlorine Poisoning ◽

Catalytic Stability ◽

Nickel Species ◽

Chloride Salts

NiCuMoLaAl mixed oxide catalysts are prepared and applied in the steam reforming of chloroform-ethyl acetate (CHCl3-EA) mixture to syngas in the present work. The pre-introduction of Cl- ions using chloride salts as modifiers aims to improve the chlorine poisoning resistance. Catalytic tests show that KCl modification is obviously advantageous to increase the catalytic life. The destruction of catalyst structure induced by in situ produced HCl and carbon deposits that occurred on acidic sites are two key points for deactivation of reforming catalysts. The presence of Cl− ions gives rise to the formation of an Ni-Cu alloy, which exhibits a synergetic effect on catalyzing reforming along with metallic Ni crystals formed from excess nickel species, and giving an excellent catalytic stability. Less CHCl3 and more steam can also increase the catalytic stable time of KCl-modified NiCuMoLaAl reforming catalyst.

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Application of microwave radiation in the grafting of acidic sites on SBA-15 type material

Journal of Porous Materials ◽

10.1007/s10934-021-01077-1 ◽

2021 ◽

Author(s):

Maciej Trejda ◽

Magdalena Drobnik ◽

Ardian Nurwita

Keyword(s):

Microwave Radiation ◽

Thermal Analyses ◽

Conventional Heating ◽

Material Surface ◽

Test Reaction ◽

Study Materials ◽

Mesoporous Support ◽

Acidic Sites ◽

Post Synthesis ◽

Adsorption Desorption

AbstractMesoporous silica of SBA-15 type was modified for the first time with 3-(trihydroxysiyl)-1-propanesulfonic acid (TPS) by post-synthesis modification involving microwave or conventional heating in order to generate the Brønsted acidic centers on the material surface. The samples structure and composition were examined by low temperature N2 adsorption/desorption, XRD, HRTEM, elemental and thermal analyses. The surface properties were evaluated by esterification of acetic acid with n-hexanol used as the test reaction. A much higher efficiency of TPS species incorporation was reached with the application of microwave radiation for 1 h than conventional modification for 24 h. It was found that the structure of mesoporous support was preserved after modification using both methods applied in this study. Materials obtained with the use of microwave radiation showed a superior catalytic activity and high stability.

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Selective catalytic reduction of NO by Co-Mn based nanocatalysts

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0240 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Vahid Zabihi ◽

Mohammad Hasan Eikani ◽

Mehdi Ardjmand ◽

Seyed Mahdi Latifi ◽

Alireza Salehirad

Keyword(s):

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Energy Dispersive ◽

Diffraction Field ◽

X Ray Diffraction ◽

X Ray ◽

Analysis Techniques ◽

Acidic Sites ◽

Temperature Window ◽

Temperature Programmed

Abstract One of the most significant aspects in selective catalytic reduction (SCR) of nitrogen oxides (NOx) is developing suitable catalysts by which the process occurs in a favorable way. At the present work SCR reaction by ammonia (NH3-SCR) was conducted using Co-Mn spinel and its composite with Fe-Mn spinel, as nanocatalysts. The nanocatalysts were fabricated through liquid routes and then their physicochemical properties such as phase composition, degree of agglomeration, particle size distribution, specific surface area and also surface acidic sites have been investigated by X-ray diffraction, Field Emission Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy, energy dispersive spectroscopy mapping, Brunauer–Emmett–Teller, temperature-programmed reduction (H2-TPR) and temperature-programmed desorption of ammonia (NH3-TPD) analysis techniques. The catalytic activity tests in a temperature window of 150–400 °C and gas hourly space velocities of 10,000, 18,000 and 30,000 h−1 revealed that almost in all studied conditions, CoMn2O4/FeMn2O4 nanocomposite exhibited better performance in SCR reaction than CoMn2O4 spinel.

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