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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Effect of Antagonistic Binder–Catalyst Interactions on Catalytic Activity in Lithium–Sulfur Batteries

Lithium-sulfur (Li-S) batteries are a promising next-generation energy storage solution, as they can reduce reliance on critical transition metals while offering high energy densities. However, their deployment is hindered by low sulfur utilization and the formation/diffusion of lithium polysulfides (LiPSs). While transition-metal catalysts and polymeric binders have been independently developed to enhance redox kinetics and LiPS adsorption, their mutual compatibility has remained largely unexplored. We show here that binder-catalyst interactions can significantly impact catalytic performance. Employing TiO 2 as a generic catalyst, the electrochemical performance is shown to depend strongly on the binder environment. TiO 2 paired with lithiated polyacrylic acid (LiPAA) shows benign interactions, resulting in enhanced cycle life. In contrast, pairing TiO 2 with protonated PAA produces antagonistic interactions that hinder Li 2 S growth. A mechanistic analysis unveils that the carboxylic H atom in PAA promotes COO − coordination to Ti sites, occupying catalytic centers and suppressing LiPS adsorption, increasing charge transfer and diffusion resistances. This phenomenon is observed across multiple catalysts, indicating that COOH-functionalized binders may broadly hinder catalytic activity. Overall, this study underscores the need for holistic cathode design and identifies binder-catalyst compatibility as an important parameter for high-performance Li-S batteries.

25 ENERGY STORAGE↗
DOE OSTI2025

Bio‐Inspired In Situ Tuning of the Hydrophobic Environment Around Catalytically Active Organic Ligand‐Stabilized Ruthenium Nanoparticles

Abstract The organic ligand environment surrounding enzymatic and homogeneous catalytic active sites often determines catalytic activity. Ruthenium nanoparticles, ≤1 nm in diameter, are synthesized using monodentate thiol, monodentate phosphine, and bidentate bisphosphine ligands. Even though some of the ruthenium surface is blocked by the ligands, catalytic activity is still observed for CO oxidation and H 2 O 2 decomposition. All three ligand‐stabilized ruthenium nanoparticles have similar CO oxidation rates; however, the bisphosphine‐stabilized Ru nanoparticles are approximately 2.5 times less active than the monothiol‐stabilized and monophosphine‐stabilized ruthenium nanoparticles for H 2 O 2 decomposition. It is observed that the organic ligand environment is modulated in situ during nanoparticle synthesis via partial oxidation of the bisphosphine as confirmed by 31 P NMR measurements. We hypothesize that bisphosphine‐bound Ru nanoparticles consist of a Ru core with some of the ligands bound in a monodentate manner where the other P atom is oxidized and not bound to the Ru surface leading to a thicker hydrophobic layer around the Ru nanoparticles. The increase in hydrophobicity is confirmed via contact angle and zeta potential measurements. H 2 O 2 decomposition rates are known to decrease with increasing hydrophobicity, and this work illustrates a pathway for increasing hydrophobicity in situ using ligand‐bound metallic nanoparticles.

Sufyan, Sayed Abu [Department of Chemical Engineer↗
DOE OSTI2021

Structural and Electronic Influences on Rates of Tertpyridine-Amine Co III -H Formation During Catalytic H 2 Evolution in an Aqueous Environment

In this paper, the differences in catalytic performance for a series of Co hydrogen evolution catalysts with different pentadentate polypyridyl ligands (L), have been rationalized by examining elementary steps of the catalytic cycle using a combination of electrochemical and transient pulse radiolysis (PR) studies in aqueous solution. Solvolysis of the [Co II -Cl] + species results in the formation of [Co II (κ 4 -L)(OH 2 )] 2+ . Further reduction produces [Co I κ 4 -L)(OH 2 )] + , which undergoes a rate-limiting structural rearrangement to [Co I (κ 5 -L)] + before being protonated to form [Co III -H] 2+ . The rate of [Co III -H] 2+ formation is similar for all complexes in the series. Using E 1/2 values of various Co species and pKa values of [Co III -H] 2+ estimated from PR experiments, we found that while the protonation of [Co III -H] 2+ is unfavorable, [CoII-H]+ reacts with protons to produce H 2 . The catalytic activity for H 2 evolution tracks the hydricity of the [Co II -H] + intermediate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

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

In this study, this work provides an innovative method for preparing different isomerization catalysts by impregnating different proportions of MgCl 2 and AlCl 3 and combining different K compounds on cellulose-derived biochar, followed by pyrolysis. Results show MgO and Al(OH) 3 existing in 4 Mg- 1 Al-C catalyst can obtain better catalytic effect on glucose isomerization than the singe of Al presenting in 0 Mg- 1 Al-C catalyst. Moreover, the synergism effects of the multi-catalytic active sites such as β-, γ -Al(OH) 3 , KCl, MgO, and K 4 H 2 (CO 3 ) 3 in Mg-Al-KHCO 3 -C catalyst can further lead to an increase in glucose isomerization, compared to the 4 Mg- 1 Al-C catalyst. The X-ray diffraction results present that the value of O/Al in Mg-Al-KHCO 3 -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 K 4 H 2 (CO 3 ) 3 ) in Mg-Al-KHCO 3 -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-KHCO 3 -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.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Dual function materials (Ru+Na 2 O/Al 2 O 3 ) for direct air capture of CO 2 and in situ catalytic methanation: The impact of realistic ambient conditions

Here a dual function material (DFM) comprised of 1% Ru, 10% Na 2 O/γ–Al 2 O 3 was studied for combined direct air capture (DAC) of CO 2 and catalytic methanation in a temperature swing operation. In the newly proposed operation, the DFM captures CO 2 (400 ppm) from air at ambient conditions. The material is then heated in H 2 to a temperature sufficient for catalytic conversion of the captured CO 2 to renewable natural gas. In this study, we demonstrate high CO 2 adsorption capacity and rates at ambient conditions (25 °C); the adsorbed CO 2 is then successfully catalytically methanated upon heating in H 2 . Adsorption was also carried out in humid conditions, more closely simulating ambient air. Adsorption and methane production were greatly improved with stable initial performance. The rate of adsorption is shown to be flowrate-dependent, which is critical for future reactor design.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Catalytic influence of light element incorporation in the lattice of palladium

The alloying of metals with foreign elements is a common approach for manipulating catalytic properties of active sites. For palladium-based catalysts, incorporation of light elements receives far less attention than Pd-metal alloys even though incorporated light element are catalytically significant. Due to their small size, light elements (H, B, C, and O) can occupy octahedral sites in Pd to form an interstitial phase, while palladium adjusts its lattice to accommodate the incorporation of larger light elements (S and P) to form distinct phases. The incorporated light element modifies the electronic structure of palladium, influencing the binding energy of substrates and reactive intermediates. Pd hydride and oxide often form in situ during hydrogenation or oxidation reactions, respectively, representing the (more, less) active phase of the catalyst. Further, the reactive interstitial hydrogen dissolved in Pd tends to hydrogenate reactants completely and unselectively. Pd oxide can be the active phase for oxidation reactions, and the incorporated oxygen or oxygen vacancies may participate in the reaction directly. Incorporated light elements change geometric aspects of Pd ensembles, serving the role of site blocking, ensemble isolation, or serve as an additional active site, endowing Pd with bifunctional character. We review the synthetic approaches for incorporating light elements into the palladium lattice. We summarize the catalytic influence of light element incorporation into the palladium lattice with respect to electronic and geometric modification, in situ incorporated hydrogen and oxygen, and discuss the influence of light element incorporation into Pd on specific reactions (i.e., selective hydrogenation, oxidation, electrocatalysis, and C—C cross coupling).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Microwave catalytic conversion of acetylene for co-production of hydrogen and carbon nanotubes

Natural gas conversion to hydrogen and solid carbon can drastically reduce the carbon footprint. Microwave plasma pyrolysis is an emerging process for chemical industries to directly convert methane (CH 4 ), the major component of natural gas, to hydrogen and carbon, which offers benefits such as fast process dynamics, flexibility, and high product yield. However, the formation of unwanted by-products, like acetylene (C 2 H 2 ), will require extra cost for gas separation. Plasma pyrolysis of CH 4 produces large amount of acetylene at downstream, which is currently used mainly for welding. Here, to avoid gas separation and upgrade acetylene from the downstream of methane plasma reactor, a novel approach toward its transformation to carbon nanotubes (CNT) and pure hydrogen (H 2 ) over Ni-based bimetallic catalyst driven by microwave irradiation has been reported in this work. The dominant gas product was hydrogen. Low concentrations of methane, ethane, and ethylene were observed in the product stream. Catalytic acetylene decomposition was carried out at 400 °C over Al 2 O 3 supported Ni catalyst. The results showed that, at 400 °C, acetylene was dehydrogenated to CNT and hydrogen was the dominant gas in product stream over 10Ni-1Pd-Al 2 O 3 catalyst. Characterizations of spent catalysts was conducted using Raman spectroscopy and transmission electron microscopy (TEM) to investigate the properties of carbon deposited over the catalyst during the catalytic acetylene decomposition. The results highlight that methane can be efficiently converted to hydrogen and CNT through 2-step process, microwave plasma and microwave catalytic conversion of intermediate acetylene, operated in a single reactor system driven by microwave.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Structural insights into RNase H catalytic mechanism from room-temperature X-ray and neutron crystallography of apo- and RNA/DNA hybrid-bound enzyme

RNase H enzymes are sequence-nonspecific endonucleases that cleave RNA strands in RNA/DNA hybrid duplexes, an enzymatic process essential in DNA replication and repair in both prokaryotes and eukaryotes. Also, RNase H activity of the reverse transcriptase in human immunodeficiency viruses (HIV-1 and HIV-2) is indispensable for the viral replication cycle. RNase H enzymes play an central role in the development of gene therapies and are targets for novel antivirals. It is therefore of great importance to gain a detailed understanding of the RNase H catalytic mechanism to improve drug design. We utilized Bacillus halodurans RNase H1 (BhRNase H1) to shed light on its function and catalytic mechanism. Room-temperature neutron crystallography of the wild-type and inactive D132N mutant enzymes revealed that E109, belonging to the catalytic DEDD motif, can change its protonation state, allowing us to propose its role in the protonation of the leaving O3′ hydroxyl group of RNA. X-ray crystallography has demonstrated the ability of the RNA/DNA duplex to slide along the protein surface upon metal ion binding at site M A , transforming a product mimic into a Michaelis-like complex, which confirms an essential role of the M A metal ion in catalysis.

Enzyme mechanisms↗
DOE OSTI2026

Mitigation of polysulfide shuttle effect in Li-S batteries through catalytic disproportionation reaction

Polysulfides are poorly retained within porous cathodes and readily diffuse into the electrolyte over time, leading to the well-known shuttle effect that undermines the reversibility of Li-S batteries. Here, in this study, we demonstrate that catalytic disproportionation of polysulfides provides an effective pathway to suppress this process by rapidly converting dissolved species into solid sulfur and sulfides, thereby preventing their migration into the electrolyte. Fundamentally, the sluggish kinetics of sulfur redox reactions are responsible for the accumulation and redistribution of soluble polysulfides in the bulk electrolyte. By accelerating these kinetics, catalyzed disproportionation not only confines sulfur within the conductive cathode matrix but also promotes the homogeneous precipitation of Li₂S₂/Li₂S, which enhances electrochemical reversibility and cycling stability. Using nitrogen-doped carbon (NC800) as a model catalyst, we reveal its ability to drive a pseudo-16-electron reduction pathway, leading to a single dominant Li₂S product and uniform deposition within the porous framework. In contrast, a non-catalytic carbon (KB) yields multiple polysulfide intermediates and heterogeneous deposition. The mechanistic insights provided here highlight the pivotal role of catalytic disproportionation in reshaping sulfur redox pathways and offer a rational strategy for mitigating polysulfide shuttling in practical Li-S pouch cells.

25 ENERGY STORAGE↗
DOE OSTI2023

Plasma catalytic non-oxidative methane conversion to hydrogen and value-added hydrocarbons on zeolite 13X

Non-thermal plasma has unfolded highly efficient, safe to operate novel routes for methane conversion to hydrogen. In this work, methane conversion is performed under atmospheric dielectric barrier discharge (DBD) plasma with and without 13X zeolite-based catalysts i.e., 13X, Ga/13X, Pd/13X, and Pd-Ga/13X. Experimental results indicate that the plasma catalytic process delivered almost twofold higher product yield than the plasma only route. The binary Pd-Ga catalyst possesses highest catalytic performance with about 40 % CH 4 conversion at an input flowrate of 5 cm 3 min -1 and 2W due to the formation of the Pd-Ga alloy, which acts as catalytic active centre for activating C–H bonds. Product yield can be tailored by the catalyst design where the bimetallic Pd-Ga/13X preferably favours the hydrocarbon formation while H 2 is the dominant product obtained over the Pd/13X. The cleavage of C–H bonds of methane molecule over the plasma only route is mainly governed by energetic electrons in the gaseous phase the catalyst activity, and plasma-catalyst synergism play a significant role in the plasma catalysis process. Further, the findings from this work provide significant insights into the methane activation for subsequent optimization of the methane conversion processes operated on floating production, storage, and offloading vessels (FPSOVs). Exploiting untapped offshore natural gas reserves, where conventional pipeline systems are less economical.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

A characterization of recombinant Arabidopsis FRIABLE1 (FRB1) reveals robust rhamnogalacturonan-I rhamnosyltransferase activity and critical catalytic residues

Plant cell walls are glycan-rich extracellular matrices that fundamentally impact essential cellular processes, such as growth, adhesion, and cell shape acquisition. Understanding plant cell wall glycans requires the identification and characterization of the biosynthetic enzymes that produce these polymers. Most successful in vitro protein expression studies of plant cell wall glycosyltransferases have relied on insect, fungal/yeast, or human cell expression systems, whereas prokaryotic expression systems have been generally unsuccessful. Here, we show that Arabidopsis FRIABLE1 (FRB1)/rhamnogalacturonan-I rhamnosyltransferase 8 (RRT8) can be produced in Escherichia coli RosettaGami2 cells as N-terminal maltose-binding protein fusion proteins containing C-terminal 6X-His-tags. We also report the catalytic constants of FRB1/RRT8 with apparent K M and K cat values of 226 μM and 33 min -1 for UDP-Rhamnose and 117 μM and 28.7 min -1 for rhamnogalacturonan-I (RG-I), respectively. We examine the catalytic activities of mutated FRB1/RRT8 proteins based on an AlphaFold 3-generated FRB1/RRT8 protein structural model with a virtually docked UDP-Rha donor. Enzymatic characterization of the mutated and wildtype FRB1/RRT8 protein confirmed that mutation of predicted catalytic site amino acid residues resulted in a 20-fold reduction in RRT activity. FRB1 also robustly polymerizes RG-I in combination with RG-I galacturonosyltransferase 1. These results show how a robust E. coli expression system combined with artificial intelligence tools can be used to increase understanding of plant cell wall glycosyltransferase structure and function.

glycosyltransferase↗
DOE OSTI2025

PFOA catalytic reaction mechanisms on zerovalent iron (Fe 0 ): A DFT investigation

In this study, density functional theory (DFT) calculations with dispersion corrections are employed to investigate catalytic reactions of perfluorooctanoic acid (PFOA) onto zerovalent iron (Fe 0 ). The main goal of this investigation is to explain the reaction mechanisms, including bond dissociation energies, activation barriers, and rate-determining steps (RDSs), of PFOA degradation. Additionally, we aim to reveal the catalytic effects of Fe 0 by comparing the reaction energy profile for the degradation of PFOA both in solution (i.e., isolated) and after adsorption on Fe 0 . Along with investigating previously reported pathways, this study proposes a new PFOA degradation pathway on Fe0. Overall, the results revealed that Fe 0 plays a key role in the catalytic degradation of PFOA, significantly affecting the RDSs and increasing defluorination rates. For instance, the activation barrier for the decarboxylation step significantly decreased from 3.08 eV to 1.11 eV over the Fe0 surface, while the activation barrier for F dissociation decreased from ∼5 eV to 0.54 eV. Additionally, the proposed pathway in this study (i.e., successive defluorination) was found to be the most favorable pathway for PFOA degradation on Fe 0 . Taken together, the DFT results are consistent with reported experimental findings and provide critical insights that will help advance the design of catalysts for PFAS degradation.

Catalysis↗
DOE OSTI2025

Effect of metal-free mesoporous silica incorporated ZSM-5 composite on thermo-catalytic pyrolysis of polypropylene

Although different zeolites impregnated with transition metals have been used in catalytic deconstruction of waste plastics to other products, the influence of hierarchical structures on conversion and product selectivity in plastic upcycling has not been thoroughly investigated. This research explores a transition metal free zeolite-based hierarchical composite, synthesized by incorporating SBA-15 in ZSM-5 framework, for efficient thermos-catalytic upcycling of polypropylene (PP). Thermogravimetric analysis reveals that ZSM-5@SBA-15 can break down PP at a significantly lower temperature, 240 °C, compared to that of pristine PP using ZSM-5 or SBA-15. In addition, pyrolysis of PP at 400 °C using ZSM-5@SBA-15 composite outperforms ZSM-5 or SBA-15 used separately and yields 90 % conversion with 70 % selectivity to propene. The presence of mesopores in the catalyst appears to reduce the diffusion resistance of intermediate products for successive scission, thereby reducing the activation energy of reaction and improving catalytic activity. In conclusion, the hierarchical composite ZSM-5@SBA-15 has significant potential for upcycling of PP into valuable monomers and lighter olefins, with lower energy demands, enhancing the economic feasibility of the process.

ZSM-5@SBA-15↗
DOE OSTI2021

Catalytic materials for lithium-sulfur batteries: mechanisms, design strategies and future perspective

Lithium-sulfur batteries (LSBs) are attractive candidates for post-lithium-ion battery technologies because of their ultrahigh theoretical energy density and low cost of active cathode materials. However, the commercialization of LSBs remains extremely challenging primarily due to poor cycling performance and safety concerns, which are inherently caused by low conductivity of S 8 and Li 2 S, severe polysulfide shuttling, and high polarization by solid Li 2 S 2 /Li 2 S deposition. Catalytic materials could facilitate the large-scale practical application of LSBs by overcoming all these challenges. In this review, we investigate the sulfur species evolution in LSBs and explore the roles of catalytic materials in charge/discharge processes, highlighting the catalysis of solid S 8 to liquid polysulfides and solid Li 2 S 2 to Li 2 S. Furthermore, we offer systematic strategies from atomic to macro levels, including defect engineering, morphology engineering and catalyst compositing, to enhance catalysis efficiency in terms of sulfur supercooling, fast charge transfer, thiosulfate generation, disulfide bond cleavage, tuneable Li 2 S growth and Li 2 S decomposition enhancement. Finally, the design and availability of the proposed catalytic materials will further advance LSB technology from coin cells and pouch cells to the subsequent commercialization scale.

25 ENERGY STORAGE↗
DOE OSTI2022

Influence of oxidizing and reducing pretreatment on the catalytic performance of CeO 2 for CO oxidation

Cerium oxide (CeO 2 ) and ceria-based materials have been extensively investigated as catalyst and support materials for various catalytic reactions, due to higher oxygen storage capacity and excellent redox properties. In the current work, we investigated the impact of pretreatment conditions (e.g., oxidation and reduction) on the physical properties of bulk CeO 2 and catalytic activity for CO oxidation as a model reaction. To understand the physical properties of pretreated CeO 2 catalysts, a suite of complementary characterization techniques, including X-ray diffraction (XRD), surface area analysis (BET), X-ray photoemission spectroscopy (XPS), and Raman spectroscopy, were applied. The results showed that a higher pretreatment temperature led to a decreased specific surface area (SSA), a decrease in oxygen vacancy/defect sites, and increased crystallite size, while surface Ce 3+ /Ce 4+ ratio did not show a specific relationship to the treatment conditions. The 700 °C treated CeO 2 samples under oxidizing and reducing conditions showed higher specific oxidation rate (μmolCO/s/m 2 ) compared to other samples at 280 and 300 °C (or < 15% CO conversion). The CO conversion per total mass of catalysts, however, decreased with increasing temperatures, especially at 700 °C under reducing condition, indicating that the catalytic performance was affected by the physical properties (SSA, oxygen vacancy/defect sites, and crystallite size).

36 MATERIALS SCIENCE↗
DOE OSTI2024

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

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 (C 2 –C 5 ) 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 the 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.

10 SYNTHETIC FUELS↗
DOE OSTI2025

Thermal Oxo-degradation and Catalytic Upgrading of Plastic Waste to Light Olefins for a Circular Economy

The commercialization of conventional pyrolysis of plastic in an inert atmosphere has been hindered by large thermal requirements stemming from long reaction rates. The rate of thermal depolymerization of waste plastics can be accelerated by the addition of oxygen in a process known as thermal oxo-degradation (TOD). This study offers the prospect of TOD to upcycle postconsumer waste rapidly and efficiently. Using moderate temperatures and small amounts of air in a fluidized bed reactor, we demonstrated that waste high-density polyethylene and polypropylene are rapidly deconstructed to condensable products. These condensable products were catalytically upgraded in a micropyrolysis reactor using commercially available zeolite (HZSM-5) to monomeric olefins. The olefin yields proved to be greater than those achieved through the catalytic upgrading of condensable products from (nonoxidative) the pyrolysis of the same plastic wastes. The coupling of TOD with catalytic upgrading proves to be an energy-efficient pathway in a plastics circular economy for the production of light olefins from wastes.

Enthalpy↗
DOE OSTI2020

Reformulated Red mud: a robust catalyst for in situ catalytic pyrolysis of biomass

Biomass feedstocks contain inorganic compounds generally classified as ash. The ash consists of compounds of potassium, calcium, magnesium, silicon, phosphorous and other elements. These elements have been reported to influence both the pyrolysis reactions as well as destabilizing the pyrolysis oils during storage. The inorganic elements have also been reported to deposit on catalyst surfaces during in situ catalytic pyrolysis leading to the eventual deactivation of acidic catalysts such as zeolites. The deposition of inorganic elements and their effect on formulated red mud (FRM) catalyst during in situ catalytic pyrolysis of pinyon juniper wood was investigated. The inorganic elements were measured for the fresh, coked, and regenerated catalysts. The BET specific surface area of the FRM catalyst decreased from 76 m2/g for the fresh catalyst to 53 m2/g for the stable regenerated catalyst. After three regenerations, the BET specific surface area stabilized at 53 m2/g and remained constant after all other regenerations. Potassium, calcium, magnesium, and phosphorous were deposited on the catalyst. Potassium deposition was linear with the number of regenerations while magnesium and calcium depositions were initially rapid but leveled off after three regenerations of the catalyst. Phosphorous deposition was almost linear, but the data were more scattered compared to potassium. The potassium deposition was attributed to physical phenomenon whereas calcium and magnesium depositions were more akin to chemical reactions related to the loss of BET surface area of the catalyst. The deposition of these elements on the surface of the catalyst did not deactivate it. After each catalyst regeneration, the oil yield was not significantly affected and the oil oxygen content and viscosity decreased slightly. This clearly showed that formulated red mud is a robust catalyst suitable for in situ catalytic fast pyrolysis of biomass.

Agblevor, Foster↗