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  1. Catalytic Upgrading of Pyrolysis Condensables from Postconsumer Polyolefins Using HZSM-5

    Brown, Jessica L. ; Radhakrishnan, Harish ; Coffman, Isabel ; ... - Energy and Fuels
    The conversion of plastic wastes to monomeric olefins is an attractive means for achieving a plastic circular economy. In our study, a fluidized bed reactor converts post-consumer waste high-density polyethylene (HDPE) and polypropylene (PP) to mostly condensed pyrolysis waxes and some oils, preventing carbon loss to gases. The pyrolysis condensables were upgraded to light olefins (C2–C5) at carbon yields greater than 76 wt % using the HZSM-5 zeolite catalyst at a post pyrolysis process that employed a micropyrolyzer. These results were comparable to olefin monomer yields from direct ex situ catalytic pyrolysis of the original waste plastics without condensing themore » vapors, highlighting the potential applicability of this approach in plastic waste recycling. Our results suggest that a centralized catalytic upgrading facility fed by pyrolysis condensables sourced from distributed thermochemical processing plants is a promising pathway to a circular economy. Such an approach enables utilization of available catalytic cracking infrastructure while focusing on setting up distributed thermochemical processing plants close to material recovery facilities. As a result, the energy-dense pyrolysis waxes are more suitable for transportation, contributing to the overall scalability and economic viability of the proposed distributed approach.« less

  2. 3D printing synthesis of catalysts

    Zhao, Xianhui ; Karakaya, Canan ; Qian, Moriko ; ... - Materials Today Sustainability
    The catalyst industry generates approximately $20 billion every year globally and plays a major role in the energy production sector. Traditional industrial catalysts (e.g., pellets) typically have mass and heat transfer limitations, and cause a pressure drop in continuous-flow reactors, lowering the efficiency of the catalytic processes. 3D printing technology has evolved rapidly over the past decade, and the 3D printing of catalysts with desired geometries can address many of the above-stated challenges with traditional catalysts. However, challenges remain to be addressed and opportunities remain to be explored before the full potential in the design and 3D printing of novelmore » catalysts can be realized. Herein this article reviews the recent development in the 3D printing of catalysts. It summarizes the 3D printing design, dimension, property, and performance of 3D printed catalysts. The applications of 3D printed catalysts, such as reforming, wastewater treatment, and CO2 capture and removal, are discussed, with a techno-economic analysis and life cycle analysis. Future research directions and opportunities for 3D printing of catalysts are also highlighted.« less

  3. Multi-catalytic active site biochar-based catalysts for glucose isomerized to fructose: Experiments and density functional theory study

    Kang, Xiheng ; You, Zi ; Huang, Yongheng ; ... - Advanced Composites and Hybrid Materials
    In this study, this work provides an innovative method for preparing different isomerization catalysts by impregnating different proportions of MgCl2 and AlCl3 and combining different K compounds on cellulose-derived biochar, followed by pyrolysis. Results show MgO and Al(OH)3 existing in 4Mg-1Al-C catalyst can obtain better catalytic effect on glucose isomerization than the singe of Al presenting in 0Mg-1Al-C catalyst. Moreover, the synergism effects of the multi-catalytic active sites such as β-, γ-Al(OH)3, KCl, MgO, and K4H2(CO3)3 in Mg-Al-KHCO3-C catalyst can further lead to an increase in glucose isomerization, compared to the 4Mg-1Al-C catalyst. The X-ray diffraction results present that themore » value of O/Al in Mg-Al-KHCO3-C catalyst is as high as 13.38, which provides many unsaturated acidic catalysis sites and benefits the glucose isomerization. Simultaneously, the TPD results reveal that the main active sites (MgO, Al(OH)3, and K4H2(CO3)3) in Mg-Al-KHCO3-C catalyst can provide weakly acidic and basic sites and avoid strongly acidic and basic sites to excessively attack the glucose. Based on the DFT analysis, the results indicate that the MgO has a great effect on the ring-opening reaction to form acyclic glucose, while Al(OH)3+ has a great effect on promoting acyclic glucose hydrogen transfer isomerized to form fructose. Compared to other carbon-based metal catalysts, the prepared Mg-Al-KHCO3-C has excellent catalytic performance, which gives a higher fructose yield (38.7%) and selectivity (87.72%) and glucose conversion (44.12%) at 100 °C in 30 min. In this study, we develop a highly efficient Mg-Al-K-biochar catalyst for glucose isomerization and provide an efficient method for cellulose valorization.« less

  4. Up up down down left right left right B A Start for the catalytic hackers of programmable materials

    Dauenhauer, Paul J. - Matter (Online)
    Catalysts have advanced over the last century to accelerate and control reactions based on static active sites. More effective catalysis can be achieved using catalysts that change with time over the course of a reaction, providing a dynamic free energy landscape that is tailored to each step in the reaction sequence. Here, the catalyst is modulated via an input program that directs the surface to change physically or electronically with time, providing information regarding the extent and duration of change optimized for specific combinations of chemistry and programmable catalyst surfaces. While in its infancy, programmable catalysis is advancing with parallelmore » efforts to establish fundamental principles of dynamic catalysts, design of programmable materials, and strategies to design input programs that will control catalysis for faster and more selective reactions.« less

  5. Atomic Layer Deposition of Cu Electrocatalysts on Gas Diffusion Electrodes for CO2 Reduction

    Lenef, Julia D. ; Lee, Si Young ; Fuelling, Kalyn M. ; ... - Nano Letters
    Electrochemical reduction of CO2 using Cu catalysts enables the synthesis of C2+ products including C2H4 and C2H5OH. Here, in this study, Cu catalysts were fabricated using plasma-enhanced atomic layer deposition (PEALD), achieving conformal deposition of catalysts throughout 3-D gas diffusion electrode (GDE) substrates while maintaining tunable control of Cu nanoparticle size and areal loading. The electrochemical CO2 reduction at the Cu surface yielded a total Faradaic efficiency (FE) > 75% for C2+ products. Parasitic hydrogen evolution was minimized to a FE of ~10%, and a selectivity of 42.2% FE for C2H4 was demonstrated. Compared to a line-of-sight physical vapor depositionmore » method, PEALD Cu catalysts show significant suppression of C1 products compared to C2+, which is associated with improved control of catalyst morphology and conformality within the porous GDE substrate. Finally, PEALD Cu catalysts demonstrated a stable performance for 15 h with minimal reduction in the C2H4 production rate.« less

  6. Propylene Metathesis over Molybdenum Silicate Microspheres with Dispersed Active Sites

    Skoda, David ; Zhu, Ran ; Hanulikova, Barbora ; ... - ACS Catalysis

  7. Synthesis of Mg–K-biochar bimetallic catalyst and its evaluation of glucose isomerization

    Kang, Xiheng ; You, Zi ; Peng, Jian ; ... - Biochar (Online)
    Highly efficient isomerization of glucose to fructose is essential for valorizing cellulose fraction of biomass to value-added chemicals. This work provided an innovative method for preparing Mg-biochar and Mg–K-biochar catalysts by impregnating either MgCl2 alone or in combination with different K compounds (Ding et al. in Bioresour Technol 341:125835, 2021, https://doi.org/10.1016/j.biortech.2021.125835 and KHCO3) on cellulose-derived biochar, followed by hydrothermal carbonization and pyrolysis. Single active substance MgO existing in the 10Mg–C could give better catalytic effect on glucose isomerization than the synergy of MgO and KCl crystalline material present in 10Mg–KCl–C. But the catalytic effect of 10Mg–C was decreased when themore » basic site of MgO was overloaded. Compared to other carbon-based metal catalysts, 10Mg–KHCO3–C with 10 wt% MgCl2 loading had excellent catalytic performance, which gave a higher fructose yield (36.7%) and selectivity (74.54%), and catalyzed excellent glucose conversion (53.99%) at 100 °C in 30 min. Scanning electron microscope–energy dispersive spectrometer and X-Ray diffraction revealed that the distribution of Mg2+ and K+ in 10Mg–KHCO3–C was uniform and the catalytic active substances (MgO, KCl and K2CO3) were more than 10Mg–C (only MgO). The synergy effects of MgO and K2CO3 active sites enhanced the pH of reaction system and induced H2O ionization to form considerable OH– ions, thus easily realizing a deprotonation of glucose and effectively catalyzing the isomerization of glucose. In this study, we developed a highly efficient Mg–K-biochar bimetallic catalyst for glucose isomerization and provided an efficient method for cellulose valorization.« less

  8. Impact of Mg on Pd-based Methane Oxidation Catalysts for Lean-burn Natural Gas Emissions Control

    Majumdar, Sreshtha Sinha ; Moses-DeBusk, Melanie ; Deka, Dhruba Jyoti ; ... - Applied Catalysis. B, Environmental
    More efficient lean-burn, natural gas engines are limited by greenhouse gas emissions due to methane oxidation catalysts (MOC) that suffer from water inhibition and high temperature activation. Herein, we report that the addition of Mg to supported 1 wt.% Pd MOCs improved hydrothermal stability even after severe hydrothermal aging. The superior methane oxidation activity compared to the corresponding Mg-free catalyst was attributed to (1) influence of Mg during surface roughening and restructuring at 700 °C on metal-support interaction, (2) reducibility of PdOx sites and (3) preferential stabilization of active Pd (1 0 0) facets in the sample as was evidencedmore » by H2 TPR and CO TPD characterization experiments. Methane conversion under synthetic exhaust conditions relevant to natural gas, lean-burn engines were investigated. In conclusion, BET, TPR, CO pulse chemisorption followed by TPD provided valuable insights into the surface area, pore volume, reducibility, Pd dispersion and Pd particle size of the selected catalyst samples.« less

  9. Synthesis, performance evaluation, and economic assessment of tailored Pt/TiO 2 catalysts for selective biomass vapour upgrading via a scalable flame spray pyrolysis route

    Kumar, Anurag ; Wang, Rongyue ; Orton, Kellene A. ; ... - Catalysis Science and Technology
    Flame-spray pyrolysis offers a scalable approach to the synthesis of tailored nanostructured catalysts for biomass conversion.

  10. Simultaneous Dehydration of Glucose and Xylose Present in a Process-Relevant Biorefinery Hydrolysate to Furfurals Using Heterogeneous Solid Acid Catalysts

    Mittal, Ashutosh ; Ruddy, Daniel A. ; Chen, Xiaowen ; ... - Energy and Fuels
...
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