@article {46595, title = {Mixed metal oxide: a new class of catalyst for methanol activation}, journal = {Applied Surface Science}, volume = {534}, year = {2020}, month = {DEC}, pages = {147449}, type = {Article}, abstract = {

In this work, we propose a mixed metal oxide as a catalyst and demonstrate it{\textquoteright}s ability to not only activate the MeOH molecule upon adsorption but also dissociate O-H and one of it{\textquoteright}s C-H bonds. MeOH activation is compared on two prominent facets of ZnAl(2)O(4 )viz. (2 2 0) and (31 1). While spontaneous O-H bond dissociation is observed on both facets, C-H bond dissociates only on the (3 1 1) surface. Multiple factors like atomic arrangement and steps on the surface, coordination of surface atoms, and their effective charges have a combined effect on MeOH activation. The (3 1 1) surface offers higher catalytic activity in comparison with (2 2 0) surface. Having a stepped surface, availability of multiple sites, and variation in the charge distribution are some of the reasons for better catalytic performance of (3 1 1) facet. Effect of orientation of MeOH with respect to the surface adds both, information and complexity to the problem. Observations pertinent to understanding this effect are also reported. A detailed analysis of atomic arrangement on the two surfaces provides a rationale as to why MeOH gets dissociated spontaneously on the mixed metal oxide. The promising results reported here opens up a new class of catalyst for research.

}, keywords = {DFT, MeOH, Spontaneous dissociation, ZnAl2O4}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2020.147449}, author = {Mehta, Shweta and Agarwal, Sheena and Kenge, Nivedita and Mekala, Siva Prasad and Patil, Vipul and Raja, T. and Joshi, Kavita} } @article {48036, title = {From molecular adsorption to decomposition of methanol on various ZnO facets: a periodic DFT study}, journal = {Applied Surface Science}, volume = {602}, year = {2022}, month = {NOV}, pages = {154150}, type = {Article}, abstract = {

Methanol is an interesting and important molecule to study because of its potential to replace existing fuels. It is also a prominent hydrogen source which can be used to generate hydrogen in-situ. ZnO is widely used as catalyst in synthesis of methanol from CO2 at industrial scale. In this work, we demonstrate that the same catalyst could be used for MeOH decomposition. We have investigated interaction of methanol with various flat and stepped facets of ZnO by employing Density Functional Theory (DFT). Two flat [(10(1)overbar 0) and (11(2)overbar 0)] and two stepped [(10(1)overbar 3) and (11(2)overbar 2)] facets are studied in detail for methanol adsorption. Chemisorption of MeOH with varying strength is common to all four facets. Most importantly spontaneous dissociation of O-H bond of methanol is observed on all facets except (11(2)overbar 0). Our DFT calculations reveal that molecular adsorption is favored on flat facets, while dissociation is favored on step facets. Also, (10(1)overbar 0) facet undergoes substantial reconstruction upon MeOH adsorption. Activation of C-H bond along with strengthening of C-O bond on ZnO facets suggest partial oxidation of methanol. With our DFT investigations, we dig deeper into the underlying electronic structure of various facets of ZnO and provide rationale for the observed facet dependent interaction of ZnO with MeOH.

}, keywords = {DFT, MeOH, Surface interactions, ZnO}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2022.154150}, author = {Mehta, Shweta and Joshi, Kavita} } @article {48695, title = {Electronic fingerprints for diverse interactions of methanol with various Zn-based systems}, journal = {Surface Science}, volume = {736}, year = {2023}, month = {OCT}, pages = {122350}, type = {Article}, abstract = {

We have investigated various Zn-based catalysts for their interaction with methanol (MeOH). MeOH is one of the most critical molecules being studied extensively, and Zn-based catalysts are widely used in many industrially relevant reactions involving MeOH. We note that the same element (Zn and O, in the present study) exhibits different catalytic activity in different environments. The changing environment is captured in the underlying electronic structure of the catalysts. In the present work, we compared the electronic structure of Zn-based systems, i.e., ZnAl2O4 and ZnO along with oxygen preadsorbed Zn (O-Zn) and metallic Zn. We demonstrate the one-to-one correlation between the pDOS of the bare facet and the outcome of that facet{\textquoteright}s interaction (i.e. either adsorption or dissociation of MeOH) with MeOH. These findings would pave the way towards the in-silico design of catalysts.

}, keywords = {DFT, Electronic properties, Methanol, Zn-based systems, ZnO}, issn = {0039-6028}, doi = {10.1016/j.susc.2023.122350}, author = {Mehta, Shweta and Joshi, Kavita} } @article {48774, title = {Hydrogen from catalytic non-thermal plasma-assisted steam methane reforming reaction}, journal = {International Journal of Hydrogen Energy}, volume = {48}, year = {2023}, month = {JUL}, pages = {24328-24341}, type = {Article}, abstract = {

Steam methane reforming reaction was carried out in a dielectric barrier plasma reactor. A systematic study is conducted to understand the influence of input power, flow rate, and water for the conversion, yield, and selectivity of the reaction over strategically designed catalysts. In particular, the production rate and selectivity of the products (H2, CO and C2 hydrocarbons) are monitored. CeO2 was used as packing material, mixed with oxides of manganese or copper and their combination. The optimum Cu/CeO2 catalyst illustrated the production rate of 248.7 mmolg-1h-1 and 11.25 mmolg-1h-1 for H2, and CO, respectively at specific energy input of 19.8 JL-1. DFT calculations exhibit apparent change in electronic structure of the CeO2 after inclusion of oxides of manganese and copper that enhance interaction with methane. Based on these findings, a plausible mechanism is elucidatedSteam methane reforming reaction was carried out in a dielectric barrier plasma reactor. A systematic study is conducted to understand the influence of input power, flow rate, and water for the conversion, yield, and selectivity of the reaction over strategically designed catalysts. In particular, the production rate and selectivity of the products (H2, CO and C2 hydrocarbons) are monitored. CeO2 was used as packing material, mixed with oxides of manganese or copper and their combination. The optimum Cu/CeO2 catalyst illustrated the production rate of 248.7 mmolg-1h-1 and 11.25 mmolg-1h-1 for H2, and CO, respectively at specific energy input of 19.8 JL-1. DFT calculations exhibit apparent change in electronic structure of the CeO2 after inclusion of oxides of manganese and copper that enhance interaction with methane. Based on these findings, a plausible mechanism is elucidated which can help to design catalyst for other applications in non-thermal plasma atmosphere. \& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

}, keywords = {DFT, Dielectric barrier discharge, Non-thermal plasma, selectivity, Specific energy input, Steam methane reforming}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2023.03.281}, author = {Bajpai, Abhinav and Mehta, Shweta and Joshi, Kavita and Kumar, Sushant} } @article {49310, title = {From digital blueprint to chemical reality: methanol to formaldehyde at ambient conditions}, journal = {Applied Surface Science}, volume = {669}, year = {2024}, month = {OCT }, pages = {160527}, type = {Article}, abstract = {

Partial oxidation of methanol to value added product presents an intriguing yet challenging process. Among these products, formaldehyde is the simplest and one of the most vital aliphatic aldehydes, which has extensive application across various domains. Industrially, silver and iron-molybdenum oxides are used as catalysts for the conversion of methanol to formaldehyde at elevated temperatures (600 degrees C and 250-400 degrees C, respectively). However, in this computational and experimental study, we have demonstrated the efficacy of ZnO as a catalyst. Notably, in the presence of ZnO, methanol readily converts to formaldehyde even under ambient conditions. We employed periodic density functional theory (DFT) to explore (10 1 1) facet of ZnO to elucidate its interaction with methanol. Our comprehensive analysis identified the most active facet (10 1 1) involved in the spontaneous conversion of methanol to formaldehyde. Subsequently, experimental validation supported our theoretical findings, demonstrating the conversion of methanol to formaldehyde with 100\% selectivity at room temperature and atmospheric pressure in the presence of ZnO. This study exemplifies the pivotal role of theory in catalyst design.

}, keywords = {DFT, Formaldehyde, MeOH, ZnO}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2024.160527}, author = {Mehta, Shweta and Kasabe, Mirabai and Umbarkar, Shubhangi B. and Joshi, Kavita} }