Nagabhatla Viswanadham

Direct bioethanol conversion into renewable 1,3-butadiene (1,3-BD) is an attractive approach toward biorefineries. The dependency on fossil-based chemicals will be minimized by using bioethanol as an alternative source. Here, the Zn-La-De-β catalyst composed of Zn and La grafted into dealuminated zeolite beta is reported for ethanol conversion to 1,3-BD. Zn and La sites were grafted into silanol nests created by the dealumination of beta zeolite to produce Zn-De-β, La-De-β, and Zn-La-De-β. These prepared catalysts were then evaluated for the conversion of bioethanol to 1,3-BD. Zn-De-β was more active for the dehydrogenation of ethanol to acetaldehyde; in contrast, La-De-β was active for 1,3-BD formation. The catalyst Zn-La-De-β, having both active sites, was most active for 1,3-BD formation and resulted in 50% C-mol selectivity for 1,3-BD at an optimized reaction temperature of 325 °C. Various characterization techniques, including XRD, XPS, CO₂-TPD, and Py-IR, realized the location and nature of active centers. This study highlights the role of each metal site in the selective production of renewable 1,3-BD. 1.38 g_1,3-BD g_cat ⁻¹ h⁻¹ was the highest productivity of 1,3-BD observed at a temperature of 325 °C and WHSV of 9.7 h⁻¹.

The present work deals with the value‐addition to bio‐derived hydrocarbon mix obtained as a side product in biorefinery for petrochemicals and fuel applications. One aspect of this study focused on developing a highly versatile, non‐noble metal‐based catalytic process to facilitate the production of green aromatics and high‐octane fuel from a renewable bio‐derived hydrocarbon mix. Considering the availability of various conventional/unconventional feedstocks viz. industrial petroleum naphtha and crude‐derived hydrocarbon mix, the catalyst development is also expanded for effective conversion of such feedstocks to produce aromatics. For this, a detailed understanding of the catalyst property‐activity relationship has been established with the help of characterization techniques like FTIR, XRD, NH ₃ ‐TPD, Pyridine‐IR, N ₂ adsorption‐desorption, HR‐TEM, XPS, TGA, etc. The studies revealed promising catalytic activity of 5Zn‐2Ga‐0.5Ba/H‐ZSM‐5 to exhibit very high aromatic selectivity (up to 80 %) and high‐octane fuel production (>100 RON) from all the feedstocks possessing different hydrocarbon composition. The catalyst showed good repeatability and recyclability at the tested reaction conditions.

This study presents a pioneering nanohybrid catalyst featuring hierarchically porous dual-functional (acid–base) active sites, which is a versatile catalyst for the crucial bio-glycerol acetalization reaction. The nanohybrid catalyst demonstrated remarkable efficiency in converting bio-diesel derived waste glycerol into excellent green fuel additive ‘solketal,’ achieving an unprecedented yield of approximately 99%. Insights into the structural properties and the relationship between the structure and properties of the catalyst were obtained through various characterization techniques, including FTIR spectroscopy, XRD, NH₃-TPD, CO₂-TPD, ²⁷Al-NMR spectroscopy, SEM, TEM, UV-Vis spectroscopy, and X-ray photoelectron spectroscopy. The hybrid catalyst shows several highly desirable properties, including enhanced acidity, a strong affinity for reactants, mesoporosity, stability, and the proximity of potent acidic and basic sites. Simplicity, cost-effectiveness, exceptional recyclability, and resistance to moisture make the synthesized MgAl-oxide/HZSM-5 (MAZ) nanohybrid catalyst an appealing candidate for potential commercial applications in bio-refinery processes.

The present study provides a novel sustainable approach for the synthesis of the ZSM-5 catalyst using biodiesel-derived waste glycerol as a green template as well as a mesopore creator, which is here reported for the first time, to the best of our knowledge. The use of bioglycerol in the preparation of ZSM-5 (Zn-Z-G and Zn-Z-T) materials exhibited a typical MFI zeolite structure, indicating glycerol played a similar role to that of a typical (TPA⁺) template in the formation of the ZSM-5 zeolite structure. The Zn-Z-G material also exhibited a large mesopore in the ZSM-5 pore structure, suggesting that glycerol played both template and mesopore creator roles. Interestingly, Zn-Z-GT prepared by the dual-template route using bioglycerol along with typical TPA⁺ showed a MFI zeolite structure with special catalytic features such as hierarchical micromesopores and well-balanced acid sites. These results reveal that the use of bioglycerol along with a typical TPA⁺ template had a promotional effect on creating such special properties in the Zn-Z-GT material. The Zn-Z-GT catalyst exhibited excellent catalytic performance in the naphtha aromatization reaction, resulting in achieving ∼58 wt % of the aromatic product and useful gas byproduct (14 wt %) with a minimum coke content (∼4 wt %) in a 12 h reaction period ascribed to its combined effect of hierarchical micromesopores and well-balanced acidity with optimum Lewis acid sites. The liquid product possessing high alkyl-aromatics with a high octane value (RON ∼ 109) produced in the present study can be used as an octane booster for liquid gasoline. The high alkyl-aromatics (>50 wt %) content of the liquid product also attracts various petrochemical applications. The effective utilization of waste bioglycerol as a green template and mesopore creator for the preparation of Zn-Z-GT can exhibit sustainability in the resultant material.

A single–pot conversion of furfural (FAL) to alkyl levulinates (AL) without using molecular hydrogen has been studied over ZSM‐5‐based Ni−W bimetallic catalysts. The metal‐metal and metal‐support interactions in the bi‐metallic catalyst are tailored by adopting appropriate synthesis protocol to conceive the superior catalytic performance. Insights on the structural properties and structure‐properties relationship of catalyst is described using the data obtained through various characterization techniques like FTIR, XRD, NH₃‐TPD, H₂‐TPR, TEM, UV‐Vis, and X‐ray photoelectron spectroscopy. The catalyst synthesis method is observed to influence catalyst properties and catalytic activity strongly. The present study indicates the formation of Ni−W bimetallic interface enhances the catalytic performance towards AL formation. However, the probability of interface formation is mainly governed by synthesis protocol. The study highlights the importance of selecting a suitable synthesis route to achieve desirable catalyst properties for obtaining enhanced catalytic performance. The Ni/W@ZSM‐5 catalyst developed in the present study exhibited excellent catalytic performance towards the production of various ALs from FAL using primary and secondary alcohols as source of hydrogen as well as reactant.