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Mohamed Assal
Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia

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Journal article
Published: 23 June 2021 in Catalysts
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Catalytic efficacy of metal-based catalysts can be significantly enhanced by doping graphene or its derivatives in the catalytic protocol. In continuation of previous work regarding the catalytic properties of highly-reduced graphene oxide (HRG), graphene-oxide (GO) doped mixed metal oxide-based nanocomposites, herein we report a simple, straightforward and solventless mechanochemical preparation of N-doped graphene (NDG)/mixed metal oxide-based nanocomposites of ZnO–MnCO3 (i.e., ZnO–MnCO3/(X%-NDG)), wherein N-doped graphene (NDG) is employed as a dopant. The nanocomposites were prepared by physical milling of separately fabricated NDG and ZnO–MnCO3 calcined at 300 °C through eco-friendly ball mill procedure. The as-obtained samples were characterized via X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), Raman, Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and surface area analysis techniques. To explore the effectiveness of the obtained materials, liquid-phase dehydrogenation of benzyl alcohol (BOH) to benzaldehyde (BH) was chosen as a benchmark reaction using eco-friendly oxidant (O2) without adding any harmful surfactants or additives. During the systematic investigation of reaction, it was revealed that the ZnO–MnCO3/NDG catalyst exhibited very distinct specific-activity (80 mmol/h.g) with a 100% BOH conversion and <99% selectivity towards BH in a very short time. The mechanochemically synthesized NDG-based nanocomposite showed remarkable enhancement in the catalytic performance and increased surface area compared with the catalyst without graphene (i.e., ZnO–MnCO3). Under the optimum catalytic conditions, the catalyst successfully transformed various aromatic, heterocyclic, allylic, primary, secondary and aliphatic alcohols to their respective ketones and aldehydes with high selectively and convertibility without over-oxidation to acids. In addition, the ZnO–MnCO3/NDG was also recycled up to six times with no apparent loss in its efficacy.

ACS Style

Mujeeb Khan; Syed Adil; Mohamed Assal; Abdulrahman Alharthi; Mohammed Shaik; Mufsir Kuniyil; Abdulrahman Al-Warthan; Aslam Khan; Zeeshan Nawaz; Hamid Shaikh; Mohammed Siddiqui. Solventless Mechanochemical Fabrication of ZnO–MnCO3/N-Doped Graphene Nanocomposite: Efficacious and Recoverable Catalyst for Selective Aerobic Dehydrogenation of Alcohols under Alkali-Free Conditions. Catalysts 2021, 11, 760 .

AMA Style

Mujeeb Khan, Syed Adil, Mohamed Assal, Abdulrahman Alharthi, Mohammed Shaik, Mufsir Kuniyil, Abdulrahman Al-Warthan, Aslam Khan, Zeeshan Nawaz, Hamid Shaikh, Mohammed Siddiqui. Solventless Mechanochemical Fabrication of ZnO–MnCO3/N-Doped Graphene Nanocomposite: Efficacious and Recoverable Catalyst for Selective Aerobic Dehydrogenation of Alcohols under Alkali-Free Conditions. Catalysts. 2021; 11 (7):760.

Chicago/Turabian Style

Mujeeb Khan; Syed Adil; Mohamed Assal; Abdulrahman Alharthi; Mohammed Shaik; Mufsir Kuniyil; Abdulrahman Al-Warthan; Aslam Khan; Zeeshan Nawaz; Hamid Shaikh; Mohammed Siddiqui. 2021. "Solventless Mechanochemical Fabrication of ZnO–MnCO3/N-Doped Graphene Nanocomposite: Efficacious and Recoverable Catalyst for Selective Aerobic Dehydrogenation of Alcohols under Alkali-Free Conditions." Catalysts 11, no. 7: 760.

Journal article
Published: 01 October 2020 in Catalysts
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In recent years, the development of green mechanochemical processes for the synthesis of new catalysts with higher catalytic efficacy and selectivity has received manifest interest. In continuation of our previous study, in which graphene oxide (GRO) and highly reduced graphene oxide (HRG) based nanocomposites were prepared and assessed, herein, we have explored a facile and solvent-less mechanochemical approach for the synthesis of N-doped graphene (NDG)/mixed metal oxide (MnCO3–ZrO2) ((X%)NDG/MnCO3–ZrO2), as the (X%)NDG/MnCO3–ZrO2 nano-composite was synthesized using physical grinding of separately synthesized NDG and pre-calcined (300 °C) MnCO3–ZrO2 via green milling method. The structures of the prepared materials were characterized in detail using X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray Analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), Raman, Thermogravimetric analysis (TGA), and N2 adsorption-desorption isotherm analysis. Besides, the obtained nanocomposites were employed as heterogeneous oxidation catalyst for the alcohol oxidation using green oxidant O2 without involving any surfactants or bases. The reaction factors were systematically studied during the oxidation of benzyl alcohol (PhCH2OH) as the model reactant to benzaldehyde (PhCHO). The NDG/MnCO3–ZrO2 exhibits premium specific activity (66.7 mmol·g−1·h−1) with 100% conversion of PhCH2OH and > 99.9% selectivity to PhCHO after only 6 min. The mechanochemically prepared NDG based nanocomposite exhibited notable improvement in the catalytic efficacy as well as the surface area compared to the pristine MnCO3–ZrO2. Under the optimal circumstances, the NDG/MnCO3–ZrO2 catalyst could selectively catalyze the aerobic oxidation of a broad array of alcohols to carbonyls with full convertibility without over-oxidized side products like acids. The NDG/MnCO3–ZrO2 catalyst were efficiently reused for six subsequent recycling reactions with a marginal decline in performance and selectivity.

ACS Style

Mufsir Kuniyil; J. V. Shanmukha Kumar; Syed Farooq Adil; Mohamed E. Assal; Mohammed Rafi Shaik; Mujeeb Khan; Abdulrahman Al-Warthan; Mohammed Rafiq H. Siddiqui; Aslam Khan; Muhammad Bilal; Hafiz M. N. Iqbal; Waheed A. Al-Masry. Eco-Friendly and Solvent-Less Mechanochemical Synthesis of ZrO2–MnCO3/N-Doped Graphene Nanocomposites: A Highly Efficacious Catalyst for Base-Free Aerobic Oxidation of Various Types of Alcohols. Catalysts 2020, 10, 1136 .

AMA Style

Mufsir Kuniyil, J. V. Shanmukha Kumar, Syed Farooq Adil, Mohamed E. Assal, Mohammed Rafi Shaik, Mujeeb Khan, Abdulrahman Al-Warthan, Mohammed Rafiq H. Siddiqui, Aslam Khan, Muhammad Bilal, Hafiz M. N. Iqbal, Waheed A. Al-Masry. Eco-Friendly and Solvent-Less Mechanochemical Synthesis of ZrO2–MnCO3/N-Doped Graphene Nanocomposites: A Highly Efficacious Catalyst for Base-Free Aerobic Oxidation of Various Types of Alcohols. Catalysts. 2020; 10 (10):1136.

Chicago/Turabian Style

Mufsir Kuniyil; J. V. Shanmukha Kumar; Syed Farooq Adil; Mohamed E. Assal; Mohammed Rafi Shaik; Mujeeb Khan; Abdulrahman Al-Warthan; Mohammed Rafiq H. Siddiqui; Aslam Khan; Muhammad Bilal; Hafiz M. N. Iqbal; Waheed A. Al-Masry. 2020. "Eco-Friendly and Solvent-Less Mechanochemical Synthesis of ZrO2–MnCO3/N-Doped Graphene Nanocomposites: A Highly Efficacious Catalyst for Base-Free Aerobic Oxidation of Various Types of Alcohols." Catalysts 10, no. 10: 1136.

Journal article
Published: 01 August 2020 in Processes
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CoxOy–manganese carbonate (X%)(CoxOy–MnCO3 catalysts (X = 1–7)) were synthesized via a straightforward co-precipitation strategy followed by calcination at 300 °C. Upon calcination at 500 °C, these were transformed to CoxOy–dimanganese trioxide i.e., (X%)CoxOy–Mn2O3. A relative catalytic evaluation was conducted to compare the catalytic efficiency of the two prepared catalysts for aerial oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) using O2 molecule as a clean oxidant without utilizing any additives or alkalis. Amongst the different percentages of doping with CoxOy (0–7% wt./wt.) on MnCO3 support, the (1%)CoxOy–MnCO3 catalyst exhibited the highest catalytic activity. The influence of catalyst loading, calcination temperature, reaction time, and temperature and catalyst dosage was thoroughly assessed to find the optimum conditions of oxidation of benzyl alcohol (BzOH) for getting the highest catalytic efficiency. The (1%)CoxOy–MnCO3 catalyst which calcined at 300 °C displayed the best effectiveness and possessed the largest specific surface area i.e., 108.4 m2/g, which suggested that the calcination process and specific surface area play a vital role in this transformation. A 100% conversion of BzOH along with BzH selectivity >99% was achieved after just 20 min. Notably, the attained specific activity was found to be considerably larger than the previously-reported cobalt-containing catalysts for this transformation. The scope of this oxidation reaction was expanded to various alcohols containing aromatic, aliphatic, allylic, and heterocyclic alcohols without any further oxidation i.e., carboxylic acid formation. The scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET) specific surface area analytical techniques were used to characterize the prepared catalysts. The obtained catalyst could be easily regenerated and reused for six consecutive runs without substantial decline in its efficiency.

ACS Style

Osamah Alduhaish; Syed Farooq Adil; Mohamed E. Assal; Mohammed Rafi Shaik; Mufsir Kuniyil; Khalid M. Manqari; Doumbia Sekou; Mujeeb Khan; Aslam Khan; Ahmed Z. Dewidar; Abdulrahman Al-Warthan; Mohammed Rafiq H. Siddiqui. Synthesis and Characterization of CoxOy–MnCO3 and CoxOy–Mn2O3 Catalysts: A Comparative Catalytic Assessment Towards the Aerial Oxidation of Various Kinds of Alcohols. Processes 2020, 8, 910 .

AMA Style

Osamah Alduhaish, Syed Farooq Adil, Mohamed E. Assal, Mohammed Rafi Shaik, Mufsir Kuniyil, Khalid M. Manqari, Doumbia Sekou, Mujeeb Khan, Aslam Khan, Ahmed Z. Dewidar, Abdulrahman Al-Warthan, Mohammed Rafiq H. Siddiqui. Synthesis and Characterization of CoxOy–MnCO3 and CoxOy–Mn2O3 Catalysts: A Comparative Catalytic Assessment Towards the Aerial Oxidation of Various Kinds of Alcohols. Processes. 2020; 8 (8):910.

Chicago/Turabian Style

Osamah Alduhaish; Syed Farooq Adil; Mohamed E. Assal; Mohammed Rafi Shaik; Mufsir Kuniyil; Khalid M. Manqari; Doumbia Sekou; Mujeeb Khan; Aslam Khan; Ahmed Z. Dewidar; Abdulrahman Al-Warthan; Mohammed Rafiq H. Siddiqui. 2020. "Synthesis and Characterization of CoxOy–MnCO3 and CoxOy–Mn2O3 Catalysts: A Comparative Catalytic Assessment Towards the Aerial Oxidation of Various Kinds of Alcohols." Processes 8, no. 8: 910.

Journal article
Published: 14 April 2020 in Molecules
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A facile, one-pot, and proficient method was developed for the production of various 2-arylaminobenzimidazoles. This methodology is based for the first time on a copper catalyst promoted domino C–N cross-coupling reaction for the generation of 2-arylaminobenzimidazoles. Mechanistic investigations revealed that the synthetic pathway involves a copper-based desulphurization/nucleophilic substitution and a subsequent domino intra and intermolecular C–N cross-coupling reactions. Some of the issues typically encountered during the synthesis of 2-arylaminobezimidazoles, including the use of expensive catalytic systems and the low reactivity of bromo precursors, were addressed using this newly developed copper-catalyzed method. The reaction procedure is simple, generally with excellent substrate tolerance, and provides good to high yields of the desired products.

ACS Style

S. N. Murthy Boddapati; Ramana Tamminana; Ravi Kumar Gollapudi; Sharmila Nurbasha; Mohamed E. Assal; Osamah Alduhaish; Mohammed Rafiq H. Siddiqui; Hari Babu Bollikolla; Syed Farooq Adil. Copper-Promoted One-Pot Approach: Synthesis of Benzimidazoles. Molecules 2020, 25, 1788 .

AMA Style

S. N. Murthy Boddapati, Ramana Tamminana, Ravi Kumar Gollapudi, Sharmila Nurbasha, Mohamed E. Assal, Osamah Alduhaish, Mohammed Rafiq H. Siddiqui, Hari Babu Bollikolla, Syed Farooq Adil. Copper-Promoted One-Pot Approach: Synthesis of Benzimidazoles. Molecules. 2020; 25 (8):1788.

Chicago/Turabian Style

S. N. Murthy Boddapati; Ramana Tamminana; Ravi Kumar Gollapudi; Sharmila Nurbasha; Mohamed E. Assal; Osamah Alduhaish; Mohammed Rafiq H. Siddiqui; Hari Babu Bollikolla; Syed Farooq Adil. 2020. "Copper-Promoted One-Pot Approach: Synthesis of Benzimidazoles." Molecules 25, no. 8: 1788.

Journal article
Published: 01 March 2020 in Catalysts
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Recently, the development of eco-friendly mechanochemical approaches for the preparation of novel catalysts with enhanced activity and selectivity has gained considerable attention. Herein, we developed a rapid and solvent-less mechanochemical method for the preparation of mixed metal oxide (Ag2O–MnO2) decorated graphene oxide (GRO)-based nanocomposites (Ag2O–MnO2/(X wt.%)GRO), as the Ag2O–MnO2/(X wt.%)GRO nanocomposite was fabricated by the physical grinding of freshly prepared GRO and pre-annealed (300 °C) mixed metal oxide nanoparticles (NPs) (Ag2O–MnO2) using an eco-friendly milling procedure. The as-prepared nanocatalysts were characterized by using various techniques. Furthermore, the nanocomposites were applied as a heterogeneous catalyst for the oxidation of alcohol by employing gaseous O2 as an eco-friendly oxidant under base-free conditions. The mechanochemically obtained GRO-based composite exhibited noticeable enhancement in the surface area and catalytic performance compared to the pristine Ag2O–MnO2. The results revealed that (1%)Ag2O–MnO2/(5 wt.%)GRO catalyst exhibited higher specific performance (13.3 mmol·g−1·h−1) with a 100% conversion of benzyl alcohol (BnOH) and >99% selectivity towards benzaldehyde (BnH) within 30 min. The enhancement of the activity and selectivity of GRO-based nanocatalyst was attributed to the presence of various oxygen-containing functional groups, a large number of defects, and a high specific surface area of GRO. In addition, the as-prepared nanocatalyst also demonstrated excellent catalytic activity towards the conversion of a variety of other alcohols to respective carbonyls under optimal conditions. Besides, the catalyst ((1%)Ag2O–MnO2/(5 wt.%)GRO) could be efficiently recycled six times with no noticeable loss in its performance and selectivity.

ACS Style

Syed Farooq Adil; Mohamed E. Assal; Mujeeb Khan; Mohammed Rafi Shaik; Mufsir Kuniyil; Doumbia Sekou; Ahmed Z. Dewidar; Abdulrahman Al-Warthan; Mohammed Rafiq H. Siddiqui. Eco-Friendly Mechanochemical Preparation of Ag2O–MnO2/Graphene Oxide Nanocomposite: An Efficient and Reusable Catalyst for the Base-Free, Aerial Oxidation of Alcohols. Catalysts 2020, 10, 281 .

AMA Style

Syed Farooq Adil, Mohamed E. Assal, Mujeeb Khan, Mohammed Rafi Shaik, Mufsir Kuniyil, Doumbia Sekou, Ahmed Z. Dewidar, Abdulrahman Al-Warthan, Mohammed Rafiq H. Siddiqui. Eco-Friendly Mechanochemical Preparation of Ag2O–MnO2/Graphene Oxide Nanocomposite: An Efficient and Reusable Catalyst for the Base-Free, Aerial Oxidation of Alcohols. Catalysts. 2020; 10 (3):281.

Chicago/Turabian Style

Syed Farooq Adil; Mohamed E. Assal; Mujeeb Khan; Mohammed Rafi Shaik; Mufsir Kuniyil; Doumbia Sekou; Ahmed Z. Dewidar; Abdulrahman Al-Warthan; Mohammed Rafiq H. Siddiqui. 2020. "Eco-Friendly Mechanochemical Preparation of Ag2O–MnO2/Graphene Oxide Nanocomposite: An Efficient and Reusable Catalyst for the Base-Free, Aerial Oxidation of Alcohols." Catalysts 10, no. 3: 281.