Seminars

Title : “Conversion of light cycle oil to monoaromatics over bifunctional catalysts in the presence of hydrogen donor”.
Venue: Thursday 25th January 2024, at 9.00 am in the Chemical Engineering Department seminar room.
Online Microsoft Teams meeting link:
https://teams.microsoft.com/l/meetup-join/19%3ameeting_MmNiYmNmZmQtOTUxYy00OWEwLTg4N2MtZjE2ZTYxODY5NDM3%40thread.v2/0?context=%7b%22Tid%22%3a%22624d5c4b-45c5-4122-8cd0-44f0f84e945d%22%2c%22Oid%22%3a%22d3ebfab0-8b57-4935-b631-6eb5c9ccf3f6%22%7d

Abstract:
The conversion of diaromatics and triaromatics present in light cycle oil (LCO) to monoaromatics such as benzene, toluene, and xylene (BTX) is studied under fluid catalytic cracking conditions over monometallic (Co, Mo, Ni, W) and bimetallic (CoMo, NiW, NiMo) catalysts supported over Mordenite, ZSM-5, Beta, Y, and Mix zeolites. Instead of H2, n-hexadecane (n-HD) is used as the hydrogen donor source at atmospheric pressure, which results in a high yield of the desired products and low coke formation. Additionally, n-HD undergoes cyclization, dehydroaromatization, and cracking as well. Bimetallic catalysts outperformed monometallic catalysts, exhibiting higher yields of total monoaromatic hydrocarbons (MAHs), BTX, and feed conversion. This improvement resulted from the formation of bimetallic oxide species and their strong interactions with the support, as evidenced by H2-TPR, XPS, and UV- DRS analyses. Bimetallic catalysts also displayed higher moderate acidity, an optimal balance of Brønsted and Lewis acid sites, and a higher hydrogen transfer index (HTI), explaining their increased BTX yield and reduced coke ormation. The study identified positive correlations between BTX yield and pore volume, surface area, and pore diameter, while a negative correlation existed with crystallite size, emphasizing the influence of structural attributes of the support on catalyst performance. Beta zeolite-supported catalysts exhibited higher total MAH yield, BTX yield, and feed conversion due to their smaller crystallite size, higher surface area, pore volume, and pore diameter. Notably, Beta zeolite, synthesized from waste fly-ash of an Indian pulp and paper industry, demonstrated good performance. The selective cracking of triaromatic compounds to diaromatics occurred rapidly, with the conversion of diaromatics governing total MAH yield, and the cracking of monoaromatic-2-ring compounds governing BTX production. Based on a detailed product characterization, reaction pathways for the conversion of diaromatics and triaromatics are proposed. Similar reactivity among alkylated naphthalene compounds suggested grouping them. A lumped kinetic model is thus developed and validated against the experimental data for bimetallic catalysts.