Search

Your search keyword '"Crocker, Mark"' showing total 477 results
Start Over Author "Crocker, Mark" Publication Year Range Last 50 years
477 results on '"Crocker, Mark"'

2. Cooperative Brønsted-Lewis acid sites created by phosphotungstic acid encapsulated metal–organic frameworks for selective glucose conversion to 5-hydroxymethylfurfural

Author

Rahaman, Mohammad Shahinur, Tulaphol, Sarttrawut, Hossain, Anwar, Jasinski, Jacek B, Sun, Ning, George, Anthe, Simmons, Blake A, Maihom, Thana, Crocker, Mark, and Sathitsuksanoh, Noppadon

Subjects
Chemical Engineering, Resources Engineering and Extractive Metallurgy, Engineering, Fluid Mechanics and Thermal Engineering, Affordable and Clean Energy, Metal-organic frameworks, Phosphotungstic acid, Encapsulation, Glucose dehydration, Hydroxymethylfurfural, Cooperative, Physical Chemistry (incl. Structural), Mechanical Engineering, Energy, Chemical engineering, Fluid mechanics and thermal engineering, Resources engineering and extractive metallurgy
Abstract

Production of 5-hydroxymethylfurfural (HMF) from biomass-derived glucose has great potential for synthesis of renewable fuels and chemicals. Selective glucose conversion to 5-hydroxymethylfurfural requires a balance between Lewis and Brønsted acids for the cascade of glucose isomerization followed by fructose dehydration. A dual Brønsted-Lewis acid, phosphotungstic acid encapsulated MIL-101(Al)–NH2 metal–organic frameworks (MOFs) was developed to catalyze the glucose dehydration reaction. The encapsulated catalysts had a high HMF selectivity of 58% at 44% glucose conversion at 120 °C in [C4C1im]Cl. Phosphotungstic acid was uniformly dispersed in the MOF pores, which provided both Brønsted and Lewis acid sites for this cascade reaction. The Brønsted acidic phosphotungstic acid-encapsulated MOF catalyst was stable and recyclable at least four times. These findings explain the effect of phosphotungstic acid location for maximizing the HMF selectivity and suggest a new approach for the design of bifunctional solid acid catalysts for selective HMF production from glucose. Moreover, the tunability of the acid properties of the encapsulated MOF catalysts provides opportunities for other biomass transformations.

Published
2022

10. Development of an Effective Au : Pd Bimetallic Heterogeneous Catalyst for Oxidative Lignin Depolymerization to Low Molecular Weight Aromatics.

Author

Karunasinghe, Gayan, Qian, Dali, Meier, Mark S., Crocker, Mark, and Martinelli, Michela

Subjects
HETEROGENEOUS catalysis, BIMETALLIC catalysts, HETEROGENEOUS catalysts, PHOTOELECTRON spectroscopy, CATALYTIC activity, LIGNIN structure, ALCOHOL oxidation
Abstract

Lignin, a phenolic‐rich biomass component, holds promise for producing value‐added products. However, its complex structure and recalcitrance present challenges for its effective utilization. To overcome this, a AuPd/Li−Al layered double hydroxide (LDH) catalyst was developed to facilitate lignin depolymerization. Various AuPd bimetallic nanoparticle compositions were supported on a basic Li−Al LDH support via a sol‐immobilization method and characterized using N2‐physisorption, X‐ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The catalysts were then evaluated in the oxidation of several benzylic alcohols using O2 as the oxidant, from which Au7Pd3/Li−Al LDH and Au1Pd1/Li−Al LDH were identified as possessing promising catalytic activity. Further investigations focused on the aerobic oxidation of β‐O‐4 linked lignin model dimers under atmospheric pressure. The tested catalysts demonstrated sequential oxidation of the model compounds, leading to cleavage of the β‐O‐4 linkage. Finally, the catalysts were applied to the oxidative deconstruction of γ‐valerolactone (GVL) extracted maple lignin at 120 °C. Au1Pd1/Li−Al LDH emerged as the most effective catalyst, yielding a range of aromatic monomers with a total monomer yield of 27 %. These results highlight the potential of the Au1Pd1/Li−Al LDH catalyst system as an eco‐friendly approach for lignin depolymerization under mild conditions. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

19. Development of Passive HC/NOx Trap Catalysts for Low Temperature Gasoline Applications

Author

Crocker, Mark, primary, Bell, Alex, additional, Van der Mynsbrugge, Jeroen, additional, Kim, Paul, additional, Gounder, Raj, additional, Lardinois, Trevor, additional, Bates, Jason, additional, Pace, Robert, additional, Ji, Yaying, additional, Lambert, Christine, additional, Theis, Joseph, additional, Getsoian, Andrew, additional, Ura, Justin, additional, Lupescu, Jason, additional, Prikhodko, Vitaly, additional, and Wei, Xinyi, additional

Published
2021
Full Text
View/download PDF

20. Towards an Integrated Process for CO2 Capture and Utilization: Cultivation of Scenedesmus acutus Using Gaseous CO2 and NH3.

Author

Vorisek, Fritz E., Ji, Yaying, Hillis, Maya H., Parker, Julia, Thompson, Jesse, Liu, Kunlei, and Crocker, Mark

Subjects
SCENEDESMUS, POISONS, ALGAL growth, CARBON sequestration, FLUE gases, TOXIC algae
Abstract

Integrating CO2 scrubbing from flue gas with its utilization in algae cultivation represents a potential means of lowering the cost of CO2 capture. Towards this goal, this study sought to assess the feasibility of using gaseous a CO2/NH3 stream, derived from CO2 capture using aqueous ammonia, as a C- and N-source for algae cultivation. Scenedesmus acutus was cultured in 800 mL photobioreactors using gaseous CO2/NH3 in mole ratios varying from 7 to 18. Excellent growth of Scenedesmus acutus was observed, the average growth rate for CO2/NH3 = 10 of 0.171 ± 0.015 g/L·day exceeding that obtained using 1% CO2/N2 and urea as the N-source (0.099 ± 0.28 g/L·day). Under optimal growth conditions (CO2/NH3 mole ratio of 10), CO2 utilization ranged from 57 to 72%, while the NH3 utilization was >90%. The CO2/NH3 feed rate was also found to exert a significant effect on algae productivity, with excessive feed rates leading to the accumulation of NH3 in the culture at concentrations that were toxic to the algae. Consequently, to avoid the toxic effects of high NH3 concentrations (>2.0 mM), it proved necessary to balance the NH3 supply with the algae growth rate so that excessive NH3 accumulation was prevented. This indicates that for practical applications, a CO2/NH3 feed control strategy would be required that takes into account the ammonium ion concentration in solution and the pH so as to avoid significant concentrations of free NH3. Analysis of the harvested biomass revealed a high protein (≥ 47 wt%) and a low ash content (< 3.6 wt%), suggesting it would be well suited for use as animal feed or as a feedstock for the production of bioplastics. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results