scholarly journals Acid Activated Palygorskite: An Efficient Solid Acid Catalyst for Acetylation Reactions - A Comparative Study

2018 ◽  
Vol 34 (6) ◽  
pp. 3106-3111
Author(s):  
Dhanya Balan A. P ◽  
Pushpaletha P
Keyword(s):  
Solid Acid ◽  
Solid Acid Catalyst ◽  
Secondary Alcohol ◽  
Acid Catalyst ◽  
Acid Sites ◽  
Acid Activation ◽  
Catalytic Activities ◽  
Modification Technique ◽  
Octahedral Cations ◽  
Catalytic Performances

Mild and efficient solid acid catalysts were prepared from natural palygorskite collected from Karnataka and Hyderabad and compared their catalytic activities using the acetylation reaction. Modification technique used for the preparation of the catalysts are acid-activation. During acid-activation exchangeable cations are replaced by H+ ions and a part of octahedral cations are dissolving and thus creating new acid sites in the crystal. The catalytic performances of these catalysts were investigated by using the acetylation reaction. Acetylation reaction was done by using different primary and secondary alcohol. Physicochemical properties were characterized by XRD, SEM, NH3-TPD measurements.

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by Perchlorated Zirconia (HClO4/ZrO2) nanoparticles as a novel solid acid catalyst

2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Seyed Yousef Mosavian
Keyword(s):  
Solid Acid ◽  
Condensation Reaction ◽  
Solid Acid Catalyst ◽  
Sol Gel ◽  
Acid Catalyst ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Zro2 Nanoparticles ◽  
Calcination Temperatures ◽  
Aldehydes And Ketones

Zirconia was synthesized in nanosize by sol-gel method and perchlorated zirconia (HClO4/ZrO2) with various calcination temperatures were prepared and characterized by XRD, FTIR and SEM techniques. The catalyst acidity characters, including the acidicstrength and the total number of acid sites were determined by potentiometric titration. The catalytic performance experiments show that the HClO4/ZrO2 with calcination temperature of 300 °C has the best catalytic activity. 2,3-Dihydroquinazolin-4(1H)-ones wereprepared in good to excellent yields via condensation reaction of oaminobenzamide and various types of aldehydes and ketones in the presence of HClO4/ZrO2 nanoparticles as an efficient solid acid catalyst. The catalyst is reusable with moderate loss in activity.

scholarly journals Preparation of a novel solid acid catalyst with Lewis and Br{\o}nsted acid sites and its application in acetalization

2014 ◽  
Vol 38 ◽  
pp. 157-163 ◽  
Author(s):  
Yijun DU ◽  
Linjun SHAO ◽  
Lingyan LUO ◽  
Si SHI ◽  
Chenze QI
Keyword(s):  
Solid Acid ◽  
Solid Acid Catalyst ◽  
Acid Catalyst ◽  
Acid Sites

Preparation of Granular Carbon‐Based Solid Acid Catalyst from White Poplar and the Catalytic Activities in Esterification

2019 ◽  
Vol 4 (30) ◽  
pp. 8855-8859
Author(s):  
Hemiao Lu ◽  
Wei Tang ◽  
Jie Ji ◽  
Xuezheng Liang ◽  
Genzhong Ji
Keyword(s):  
Solid Acid ◽  
Solid Acid Catalyst ◽  
Acid Catalyst ◽  
White Poplar ◽  
Catalytic Activities ◽  
Carbon Based

scholarly journals Acid Properties of GO and Reduced GO as Determined by Microcalorimetry, FTIR, and Kinetics of Cellulose Hydrolysis-Hydrogenolysis

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1393
Author(s):  
Van Chuc Nguyen ◽  
Sarah Kheireddine ◽  
Amar Dandach ◽  
Marion Eternot ◽  
Thi Thu Ha Vu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Solid Acid ◽  
Solid Acid Catalyst ◽  
High Mobility ◽  
Acid Catalyst ◽  
Strong Acid ◽  
Cellulose Hydrolysis ◽  
Acid Sites ◽  
Pyridine Adsorption ◽  
Nh3 Adsorption

Graphene oxide addresses increasing interests as a solid acid catalyst working in water for carbohydrate conversion. If there is a general agreement to correlate its unique catalytic performances to its ability to adsorb sugars, the origin of its acidity remains controversial. In this article, we study the acid strength of graphene oxide (GO) prepared by modified Hummers method and that of reduced GO by calorimetry of NH3 adsorption and by FTIR of pyridine adsorption. Very strong acid sites are detected on GO by calorimetry, while reduced graphene oxide (reGO) is not very acidic. The FTIR of pyridine adsorption shows the prevailing presence of Br∅nsted acid sites and a unique feature, the presence of pyridine coordinated by hydrogen bonds. This exceptionally strong Br∅nsted acidity is tentatively explained by the presence of graphene domains decorated by hydroxyl, carboxylic, or sulfonated groups within the GO sheet, resulting in a high mobility of the negative charges which makes the proton free and explains its strong acidity. Accordingly, only GO is active and selective for native cellulose hydrolysis, leading to 27% yield in glucose. Finally, we show that sugar alcohols cannot be formed directly from cellulose using GO combined with Pt/re-GO under hydrogen, explained by the reduction of oxygenated functions of GO. The instability of the functional groups of GO in a reducing atmosphere is the weak point of this peculiar solid acid.

scholarly journals Nanostructured zeolite with brain-coral morphology and tailored acidity: a self-organized hierarchical porous material with MFI topology

CrystEngComm ◽  
2020 ◽  
Vol 22 (38) ◽  
pp. 6275-6286
Author(s):  
Esun Selvam ◽  
Rajesh K. Parsapur ◽  
Carlos E. Hernandez-Tamargo ◽  
Nora H. de Leeuw ◽  
Parasuraman Selvam
Keyword(s):  
Solid Acid ◽  
Solid Acid Catalyst ◽  
High Surface ◽  
High Surface Area ◽  
Acid Catalyst ◽  
Acid Sites ◽  
Diffusion Resistance ◽  
Self Organized ◽  
Hierarchical Porous ◽  
Coral Morphology

Nano-zeolite with brain-coral morphology formed by self-organization of ultra-small nanospheres, exhibits micro/meso porosity with high surface area, distributed acid sites, and reduced diffusion resistance making it a promising solid acid catalyst.

scholarly journals Chromium oxide zirconia solid acid catalyst for n-pentane isomerization

2014 ◽  
Vol 10 (4) ◽  
Author(s):  
Nur Hazirah Rozali Annuar ◽  
Aishah Abdul Jalil ◽  
Sugeng Triwahyono
Keyword(s):  
Physical Properties ◽  
Surface Area ◽  
Chromium Oxide ◽  
Solid Acid ◽  
Solid Acid Catalyst ◽  
Sol Gel ◽  
Acid Catalyst ◽  
Acid Sites ◽  
Bet Surface Area ◽  
Gel Technique

New catalyst based on zirconia (ZrO2) supported by chromium oxide (CrO3) for isomerization of n-pentane was studied. CrO3-ZrO2 was prepared with chromium nitrate by the titration and sol-gel technique. The physical properties of the catalysts were characterized by XRD, BET surface area analyzer, and TEM. The acidity and structure of catalysts were determined by pyridine and lutidine preadsorbed FTIR spectroscopy.  The isomerization of n-pentane was carried out at 523 K under hydrogen stream. CrO3-ZrO2 shows the differences in terms of physical properties where the introduction CrO3 partially eliminated the monoclinic phase of ZrO2 and developed new peaks assigned to tetragonal phase of ZrO2. CrO3-ZrO2 also shows a higher specific surface area where it increases in the pore volume of the catalyst compare to its parent zirconia.  The IR results indicated that CrO3-ZrO2 catalyst have strong Lewis and weak Brønsted acid sites. The conversion of n-pentane for CrO3-ZrO2 was 32% respectively, while the selectivity to iso-pentane was 100%. ________________________________________GRAPHICAL ABSTRACT

scholarly journals Interesterification for biofuel synthesis over HJ-2# caly-supported SO42-/ZrO2 solid acid catalyst

2021 ◽  
Vol 290 ◽  
pp. 01033
Author(s):  
Dong Lixin ◽  
Zhang Xueqiong ◽  
Chen Jing ◽  
Hao Yinan ◽  
Pang Liwen ◽  
...  
Keyword(s):  
Soybean Oil ◽  
Solid Acid ◽  
Solid Acid Catalyst ◽  
Maximum Yield ◽  
Acid Catalyst ◽  
Acid Sites ◽  
Preparation Condition ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Ft Ir

This study makes use of soybean oil to produce biodiesel using SO42-/ZrO2-HJ-2# caly solid acid catalyst (SZ-HJ-2#). It was through coprecipitation and impregnation method that the catalyst was prepared which was then characterized by means of FE-SEM, XRD, EDS, BET, FT-IR, ICP-MS, NH3-TPD and XPS. The catalytic property of the synthesized catalyst was determined by using it to produce biodiesel from soybean oil. A study was carried out to find the effect of the different preparation condition of catalyst affecting the process. For SZ-HJ-2#, Optimized condition of 0.5 mol/L(zirconium salt solution), 1.5 mol/L (the concentration of sulfuric acid impregnating solution) and 450℃(calcination temperature). Optimized conditions of 8.32:1 methanol to soybean oil molar ratio and catalytic loading of 1 wt% at 55℃ with a stirring rate of 500 rpm for a reaction duration of 10 h gave a maximum yield of 89.6 wt%. Moreover, the further investigation indicated the catalytic activities were closely related to the ratio of Brönsted acid sites and intensity on catalysts. Besides, the excellent performance of the catalyst during recycling was shown by conducting reusability study.

Efficient Solid Acid Catalyst Containing Lewis and Brønsted Acid Sites for the Production of Furfurals

ChemSusChem ◽  
2014 ◽  
Vol 7 (8) ◽  
pp. 2342-2350 ◽  
Author(s):  
Michael G. Mazzotta ◽  
Dinesh Gupta ◽  
Basudeb Saha ◽  
Astam K. Patra ◽  
Asim Bhaumik ◽  
...  
Keyword(s):  
Solid Acid ◽  
Solid Acid Catalyst ◽  
Acid Catalyst ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

scholarly journals Mesoporous Porphyrin-Silica Nanocomposite as Solid Acid Catalyst for High Yield Synthesis of HMF in Water

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2519
Author(s):  
Arindam Modak ◽  
Akshay R. Mankar ◽  
Kamal Kishore Pant ◽  
Asim Bhaumik
Keyword(s):  
Sulfonic Acid ◽  
Solid Acid ◽  
Solid Acid Catalyst ◽  
High Surface ◽  
High Surface Area ◽  
Acid Catalyst ◽  
Acid Sites ◽  
Environmental Research ◽  
Organic Polymer ◽  
High Yield

Solid acid catalysts occupy a special class in heterogeneous catalysis for their efficiency in eco-friendly conversion of biomass into demanding chemicals. We synthesized porphyrin containing porous organic polymers (PorPOPs) using colloidal silica as a support. Post-modification with chlorosulfonic acid enabled sulfonic acid functionalization, and the resulting material (PorPOPS) showed excellent activity and durability for the conversion of fructose to 5-hydroxymethyl furfural (HMF) in green solvent water. PorPOPS composite was characterized by N2 sorption, FTIR, TGA, CHNS, FESEM, TEM and XPS techniques, justifying the successful synthesis of organic networks and the grafting of sulfonic acid sites (5 wt%). Furthermore, a high surface area (260 m2/g) and the presence of distinct mesopores of ~15 nm were distinctly different from the porphyrin containing sulfonated porous organic polymer (FePOP-1S). Surprisingly the hybrid PorPOPS showed an excellent yield of HMF (85%) and high selectivity (>90%) in water as compared to microporous pristine-FePOP-1S (yield of HMF = 35%). This research demonstrates the requirement of organic modification on silica surfaces to tailor the activity and selectivity of the catalysts. We foresee that this research may inspire further applications of biomass conversion in water in future environmental research.

scholarly journals Selective Hierarchical Aluminosilicates for Acetalization Reaction with Propylene Glycol

2019 ◽  
Vol 19 (4) ◽  
pp. 975 ◽  
Author(s):  
Hartati Hartati ◽  
Mardi Santoso ◽  
Hadi Nur ◽  
Leaw Wai Loon ◽  
Hasliza Bahruji ◽  
...  
Keyword(s):  
Propylene Glycol ◽  
High Selectivity ◽  
Solid Acid ◽  
Solid Acid Catalyst ◽  
Acid Catalyst ◽  
Acid Sites ◽  
Mesoporous Aluminosilicates ◽  
Adsorption Analysis ◽  
The Hierarchical Structure ◽  
Acetalization Reaction

Hierarchical micro-mesoporous aluminosilicates nanoparticles were synthesized at different of Si/Al ratios and were directly used as a solid acid catalyst for acetalization reaction with propylene glycol. TEM and N2 adsorption analysis of the resulting aluminosilicates revealed the formation of the hierarchical structure occurs on the Si/Al ratio increases the formation of mesoporous within the structure of aluminosilicate. The aluminosilicates exhibit high selectivity towards acetalization reaction in comparison with the homogeneous PTSA. The presence of mesoporous structures is crucial for increased conversion and selectivity of the reaction which presumably due to the improved diffusion of substrate to reach acid sites.

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