Catalysis and Reaction Engineering Commons^™

The Investigation Of Surface Barrier During Molecular Transport In Hierarchical Zeolites, Xiaoduo Qi

Doctoral Dissertations

Hierarchical zeolites with micropore lengths on the order of nanometers have been synthesized with the aim of reducing mass transfer limitation. However, due to large external surface to volume ratios, the mass transport in these materials can be hindered by a secondary rate limitation step imposed on the external surface of the zeolites. This has led to the general phenomenon referred to as “surface barriers”, which cause the enhancement in mass transport being far lower than expected. In order to fully unlock the potential of hierarchical zeolites, it is imperative to fundamentally understand the molecular transport in these new types …

Creating Renewable Tunable Polymers From Hydroxymethylfurfural, Meredith C. Allen

Electronic Theses and Dissertations

The research here deals with the conversion of 5-hydroxymethylfurfural (HMF) into a tunable polymer. HMF is a known derivative that can be acquired from biomass via hydrolysis of cellulose followed by isomerization and finally selective dehydration. The process considered here is being developed to create tunable polymers from HMF and involves several different steps, three of which are covered here. The first step, an etherification, is the reaction of HMF with an alcohol. This step is significant because in this step the R-group from the alcohol is added to HMF and the branching portion formed is carried over to the …

Nanoporous Solid Acid Materials For Biomass Conversion Into Value-Added Chemicals: Synthesis, Catalysis, And Chemistry, Hong Je Cho

Doctoral Dissertations

Growing environmental concerns associated with diminishing reserves of fossil fuels has led to accelerated research efforts towards the discovery of new catalytic processes for converting renewable lignocellulosic biomass into value-added chemicals. For this conversion, nanoporous solid acid materials have been widely used because of their excellent hydrothermal stability and molecular sieving capability. In the thesis, hierarchical Lewis acid zeolites with ordered mesoporosity and MFI topology (three dimensionally ordered mesoporous imprinted (3DOm-i) Sn-MFI) were successfully synthesized within the confined space of three dimensionally ordered mesoporous (3DOm) carbon by a seeded growth method. The obtained 3DOm-i Sn-MFI showed at least 3 times …

Catalytic Hydrodeoxygenation And Dehydration Of Bioderived Oxygenates To Renewable Hydrocarbon Building Block Molecules: Enabling Renewable Carbon Fiber, Andrew Walter Lepore

Doctoral Dissertations

It is our goal to develop inexpensive catalytic pathways that can effectively remove oxygen from bio-derived carboxylic acids and alcohols under mild reaction conditions to produce propene which can be converted to renewable carbon fibers. Carboxylic acid hydrodeoxygenation and alcohol dehydration are necessary for successfully producing propene from bio-mass derived precursors and are also broadly relevant to bio-oil upgrading. This body of research adds to the understanding of both known and novel catalyst materials and develops and optimizes pathways for valorizing oxygenates. Dehydration and hydrodeoxygenation catalysts were examined under both batch and continuous flow operation. Product selectivity and reactant conversion …

Microwave And Ultrasound Assisted Zeolitization Of Coal Fly Ash, Syed Salman Raza Bukhari

Electronic Thesis and Dissertation Repository

Coal fly ash (CFA) is a major bi-product of coal fired power plants and is a liability for coal power industry. Coal fly ash has been accumulating rapidly around the globe and has been known to be accident prone, resulting in $1.65 billion in clean-up costs and fines. Given the environmental damage CFA is capable of causing, it is a great interest for scientists to recycle this material. Utilization of novel energy such as microwave and ultrasound has been of research interest for the zeolitization of coal fly ash.

This research produced zeolites from CFA utilizing microwave and ultrasound power. …

Rational Development Of Solid Lewis Acid Catalysts For Biomass Conversion, Chun-Chih Chang

Doctoral Dissertations

The need for sustainable production of everyday materials in addition to declining reserves of petroleum-based feedstocks has motivated research into the production of renewable aromatic chemicals from biomass. We have proposed a multistep pathway to produce renewable p-xylene from lignocellulosic biomass using heterogeneous catalysts. The pathway includes formation of glucose by saccharification of cellulose, isomerization of glucose into fructose, dehydration/hydrogenolysis for production of 2,5-dimethylfuran (DMF), and final step for producing p-xylene from reacting DMF with ethylene. Lewis acid zeolite catalysts (e.g. Sn-BEA, a tin containing molecular sieve with zeolite BEA structure) exhibited critical roles in the pathway because …

Production Of Sustainable Aromatics From Biorenewable Furans, Christopher Luke Williams

Doctoral Dissertations

Increasing demand for renewable and domestic energy and materials has led to an accelerated research effort in developing biomass-derived fuels and chemicals. The North American shale gas revolution can provide a domestic source for the manufacture of four of the five major products of the world chemical industry: methanol, ethylene, ammonia, and propylene. However this emerging domestic resource lacks a conversion pathway to the fifth major chemical building block; the larger C6 aromatics benzene, toluene, and xylene (BTX). One sustainable feedstock for renewable C6 aromatic chemicals is sugars produced by the saccharification of biopolymers (e.g., cellulose, hemicellulose). The catalytic conversion …

Production Of Renewable Fuels And Chemicals From Biomass-Dervied Furan Compounds, Sara K. Green

Doctoral Dissertations

Growing concern over the petroleum supply, energy independence, and environmental impacts associated with fossil fuels, has motivated research into the production of renewable fuels and aromatic chemicals from biomass resources. Specifically, furan-based feedstocks such as furfural, 2-methylfuran (MF) and, 2,5-dimethylfuran (DMF) can be derived from biomass and used to produce a wide variety of desired compounds. These furan-based feedstocks are produced by: (a) the hydrolysis of cellulose and hemicellulose form to glucose and xylose, (b) the dehydration of these carbohydrates to form 5-hydroxymethylfurfural (HMF) and furfural, and (c) the reduction of HMF and furfural to DMF, MF, and furan. The …

Fast Catalytic Oxidation Of Phenol Over Modified Zeolite L Nanocrystals, Eng-Poh Ng Dr.

Eng-Poh Ng

Iron modified zeolite L nanocrystals (Fe/KL) were synthesized hydrothermally by the incorporation of Fe3+ in zeolite L lattice. XRD results showed an increase in the inter-planar spacing and lattice parameters. Transition characteristic of the tetrahedral Fe3+ species were observed in the UV–Vis spectrum. The oxidation of phenol in the presence of acetic acid over Fe/KL gave 93.40% conversion in 30 min with selective formation of 77.47% catechol and 22.53% hydroquinone. The catalytic activity was significantly enhanced by the addition of acetic acid. It was found that the acetic acid was oxidized by hydrogen peroxide to form peracetic acid, which served …

Nanosized Molecular Sieves Utilized As An Environmentally Friendly Alternative To Antioxidants For Lubricant Oils, Eng-Poh Ng Dr.

Eng-Poh Ng

Lubricants play a significant part in current environmental considerations since they are an integral and indispensable component of modern technology. The production, application and disposal of the lubricants have to follow increasingly strict requirements for protecting the environment and living organisms. In this respect, molecular sieve (LTL type zeolite) is investigated as a potential environmentally friendly alternative to traditional antioxidant additives for lubricant oils. Accelerated oxidation experiments using pure base oil and additivated base oil in the presence of the LTL molecular sieve are carried out in parallel, and the oxidation processes are monitored by FT-IR spectroscopy, spectrophotometry, chromatography, total …

Alpo-18 Seed Layers And Films By Secondary Growth, Lubomira Tosheva, Eng-Poh Ng, Svetlana Mintova, Manfred Holzl, Till H. Metzger, Aidan M. Doyle

Eng-Poh Ng

AlPO-18 layers were prepared on Si wafers via spin-coating or the Langmuir−Blodgett (LB) method using nanosized crystals. Multilayers were deposited by spin-coating, whereas the seeds assembled by the LB technique were monolayers. The seeded layers were not stable upon secondary growth under microwave radiation, and no films were formed on the supports. Dense AlPO-18 films could be obtained by secondary growth after stabilization of the seed layers by adding prehydrolyzed tetraethylorthosilicate (TEOS) to the colloidal AlPO-18 suspension prior to support seeding. The stabilized seed layers and the grown AlPO-18 films were stable. The structure and the morphology of the films …

Environmentally Benign Synthesis Of Nanosized Aluminophosphate Enhanced By Microwave Heating, Eng-Poh Ng, Luc Delmotte, Svetlana Mintova

Eng-Poh Ng

The problem addressed with our paper is on the efficient utilization of reacting materials for enhanced syntheses of nanosized aluminophosphate molecular sieve by microwave heating, and decreasing or almost eliminating the related waste. The synthesis procedure deals with the environmental issues concerning the future manufacture re-use and disposal of non-reacted chemicals associated with the production of nanosized aluminophosphate. Nanosized AlPO-18 has been prepared by a multicycle synthesis approach via re-using non-reacted compounds from precursor suspensions with minimal requirement of chemical compensation after recovering of crystalline nanoparticles from each step. This approach is implied as environmentally benign and results in almost …