@article {49014, title = {Experimental and kinetic modelling studies for the design of fixed bed methanol reactor over CuZA catalyst}, journal = {Chemical Engineering Research Design }, volume = {205}, year = {2024}, month = {MAY}, pages = {79-90}, type = {Article}, abstract = {

Direct conversion of CO 2 via hydrogenation to value-added chemicals is a vital approach for utilising CO 2 emitted into the atmosphere. In this paper, a critical analysis of reaction kinetic modelling studies is explored in a fixed bed reactor to improve methanol yield for different H 2 to CO 2 ratios by simulating a lab-scale reactor for adiabatic and isothermal conditions. The feed inlet temperature and pressure variations are applied to study the effect of both configurations on methanol production. The results show that the isothermal configuration yields 2.76\% more methanol yield compared to the adiabatic reactor. The effect of H 2 to CO 2 molar ratios of 3, 6 and 9 on the performance of the catalyst and the influence of CO and CO 2 hydrogenation is investigated with model simulations. The overall methanol yield is increased from 19.03\% to 36.41\% with increase in H 2 to CO 2 molar ratio from 3 to 9. Experiments are performed using commercial copper-based catalyst for different temperatures of 210, 230 and 250 degrees C at a pressure of 40 bar for H 2 /CO 2 of 3 and GHSV of 720 h -1 as well as at optimal temperature of 250 degrees C and 50 bar with varying H 2 /CO 2 of 3, 6, 9 for 3 g and 6 g catalyst. The maximum methanol yield of 2.53\% and space time yield of 13.59 mg/g cat .h is obtained at H 2 /CO 2 ratio of 9.

}, keywords = {CO2 conversion, CuZA catalyst, H2 toCO2 molar ratio, Kinetic modelling, Methanol}, issn = {0263-8762}, doi = {10.1016/j.cherd.2024.03.032}, author = {Bagwan, Farahanaz M. and Dongapure, Pavan and Kulkarni, Amol A. and Vasireddy, Satyam Naidu} } @article {49409, title = {Evaluation of reaction kinetics for chemoselective hydrogenation of citral for intensification of citral intermediates using copper-based catalysts}, journal = {Indian Chemical Engineer}, volume = {67}, year = {2025}, month = {MAR}, type = {Article}, abstract = {

Citral intermediates{\textquoteright} formation kinetics is studied using non-noble metal catalyst (Cu/SiO2) to evaluate catalyst performance characteristics via chemoselective hydrogenation of citral. The catalyst is synthesised by the precipitation method and characterised using XRD, FESEM and BET surface area analyser. Hydrogenation experiments are carried out using an Autoclave reactor in the temperature range of 80{\textendash}120{\textdegree}C, pressure range of 10{\textendash}50 bar and for catalyst loadings of 0.5, 1 and 1.5 g. The intermediates product distribution comprises aldehyde and alcohol formation such as citronellal, nerol and citronellol formation. The performance of the Cu/SiO2\ catalyst is evaluated using the parameters such as citral conversion, citronellol selectivity and yield as 96.96\%, 95.30\% and 92.30\%, respectively under optimal conditions of 50 bar, 120{\textdegree}C and 1 g catalyst for the reaction time of 100 min. The absence of internal and external mass transfer limitations is verified using the Carberry number and Weisz-Prater modulus criterion. The intrinsic kinetics of the gas{\textendash}liquid phase hydrogenation of citral is determined using the Langmuir{\textendash}Hinshelwood-Hougen-Watson (LHHW) model for citral intermediates formation. The reaction kinetic parameters show that citronellol formation favours by the nerol route compared to citronellal conversion.

}, doi = {https://doi.org/10.1080/00194506.2024.2390068}, author = {Debtirtha, Banik and Kinage, Anil K. and Vasireddy, Satyam Naidu} } @article {49787, title = {Experimental investigation and lumped kinetic modeling studies for upcycling of polyolefins}, journal = {Journal of the Indian Chemical Society}, volume = {102}, year = {2025}, month = {NOV}, pages = {102127}, type = {Article}, abstract = {

The present work discusses on comparative kinetic analysis of the pyrolysis of polypropylene (PP), high-density polyethylene (HDPE), and low-density polyethylene (LDPE) using sophisticated lumped models. Unlike many previous studies that focused on single-polymer kinetic models or employed simplified reaction schemes, this study develops an enhanced multistep reaction network that explicitly considers both primary decomposition and secondary cracking pathways, thereby improving the accuracy of product distribution predictions. By integrating this detailed reaction framework with a robust nonlinear regression approach using LSQNONLIN and ODE45 solvers in MATLAB, the study achieved greater accuracy in estimating kinetic parameters than traditional curve-fitting methods. The findings reveal that HDPE exhibits the highest activation energy (222.97 kJ mol(-1)), indicating it is more thermally stable than LDPE (193.44 kJ mol(-1)) and PP (62.16 kJ mol(-1)). One of the highlights of the present work is that lower pyrolysis temperature (400 degrees C) is found to be optimum for liquid yield by reducing secondary cracking, which aligns with the sustainable fuel production principles. The study also emphasizes on the limitations of previous lumped models that overlooked wax decomposition pathways, which are crucial for optimizing the hydrocarbon distribution. Future research should investigate catalytic interventions and reactor design modifications to enhance the product selectivity and scalability. This study offers a more comprehensive kinetic framework for advancing the valorization of plastic waste through pyrolysis, aiding the development of efficient waste-to-fuel conversion strategies.

}, keywords = {Lumped kinetic modeling, Plastic pyrolysis, Rate constants, Reaction pathways, Secondary cracking reactions, Temperature-dependent product distributions}, issn = {0019-4522}, doi = {10.1016/j.jics.2025.102127}, author = {Kavade, Omkar G. and Dhepe, Paresh L. and Devi, Nandini R. and Vasireddy, Satyam Naidu} }