Catalytic Conversion of Alkenes on Acidic Zeolites: Automated Generation of Reaction Mechanisms and Lumping Technique

Abstract

Acid-catalyzed hydrocarbon transformations are essential for industrial processes, including oligomerization, cracking, alkylation, and aromatization. However, these chemistries are extremely complex, and computational (automatic) reaction network generation is required to capture these intricacies. The approach relies on the concept that underlying mechanisms for the transformations can be described by a limited number of reaction families applied to various species, with both gaseous and protonated intermediate species tracked. Detailed reaction networks can then be tailored to each industrially relevant process for better understanding or for application in kinetic modeling, which is demonstrated here. However, we show that these networks can grow very large (thousands of species) when they are bound by typical carbon number and rank criteria, and lumping strategies are required to decrease computational expense. For acid-catalyzed hydrocarbon transformations, we propose lumping isomers based on carbon number, branch number, and ion position to reach high carbon limits while maintaining the high resolution of species. Two case studies on propene oligomerization verified the lumping technique in matching a fully detailed model as well as experimental data.

Plasma Nanoengineering of Bioresource-Derived Graphene Quantum Dots as Ultrasensitive Environmental Nanoprobes

“…These results imply a possibility that vinyl and ethylene might be the main intermediates for the GQD synthesis. Unsaturated hydrocarbons such as acetylene, ethylene, and vinyl are the main feed for the production or aromatization of benzene and its derivatives. − However, the process requires high temperature and pressure that go up to 1000 K and 20 bar, respectively. Despite that fact, our microplasma system can promote the whole GQD synthesis, starting from the precursor deconstruction, benzene formation, and even growth of GQDs in an environmentally friendly manner, inferring a step toward green and sustainable societies.…”

Mechanisms of Light Alkene Oligomerization on Metal-Modified Zeolites

“…Oligomerization is the dominant reaction route for light alkenes adsorbed on H-form zeolites at 296–373 K. ,− At these temperatures, alkene oligomerization is instantaneous and yields a range of oligomers, with the product distribution influenced by the shape selectivity effect and concurrent isomerization. ,,,− Note that zeolite BAS can also catalyze other alkene reactions (isomerization, β-scission, hydrogen transfer, etc. ), , especially at temperatures above 500 K, which constitute the reaction network of possible interconnected transformations sometimes referred to as oligomerization in a broader sense. − Additionally, at T > 673 K, alkenes can be produced by dealkylation of alkyl-substituted aromatic compounds in line with the hydrocarbon pool concept. , Here we will only focus on the mechanistic aspects of the so-called true oligomerization step which essentially provides the elongation of the hydrocarbon chain.…”

Concentration‐Flux‐Steered Mechanism Exploration with an Organocatalysis Application

“…Commonly, micro-kinetic modeling is employed as an a-posteriori analysis step after the automated construction of the reaction network has been finished. For instance, the computer programs NETGEN [12][13][14][15][16] and EXGAS [17] automatically construct reaction networks from graph-based reactivity rules, which are then analyzed by micro-kinetic modeling. Similarly, the program RMG [18][19][20][21] generates reaction networks and derives a reaction mechanism by analyzing the concentration fluxes through the network.…”