Direct Detection of Products from the Pyrolysis of 2-Phenethyl Phenyl Ether

The pyrolysis of 2-phenethyl phenyl ether (PPE, C_6H_5C_2H_4OC_6H_5) in a hyperthermal nozzle (300-1350 °C) was studied to determine the importance of concerted and homolytic unimolecular decomposition pathways. Short residence times (<100 μs) and low concentrations in this reactor allowed the direct detection of the initial reaction products from thermolysis. Reactants, radicals, and most products were detected with photoionization (10.5 eV) time-of-flight mass spectrometry (PIMS). Detection of phenoxy radical, cyclopentadienyl radical, benzyl radical, and benzene suggest the formation of product by the homolytic scission of the C_6H_5C_2H_4-OC_6H_5 and C_6H_5CH_2-CH_2OC_6H_5 bonds. The detection of phenol and styrene suggests decomposition by a concerted reaction mechanism. Phenyl ethyl ether (PEE, C_6H_5OC_2H_5) pyrolysis was also studied using PIMS and using cryogenic matrix-isolated infrared spectroscopy (matrix-IR). The results for PEE also indicate the presence of both homolytic bond breaking and concerted decomposition reactions. Quantum mechanical calculations using CBS-QB3 were conducted, and the results were used with transition state theory (TST) to estimate the rate constants for the different reaction pathways. The results are consistent with the experimental measurements and suggest that the concerted retro-ene and Maccoll reactions are dominant at low temperatures (below 1000 °C), whereas the contribution of the C_6H_5C_2H_4-OC_6H_5 homolytic bond scission reaction increases at higher temperatures (above 1000 °C)

Supported molybdenum oxides as effective catalysts for the catalytic fast pyrolysis of lignocellulosic biomass

The catalytic fast pyrolysis (CFP) of pine was investigated over 10 wt% MoO[subscript 3]/TiO[subscript 2] and MoO[subscript 3]/ZrO[subscript 2] at 500 °C and H[subscript 2] pressures ≤0.75 bar. The product distributions were monitored in real time using a molecular beam mass spectrometer (MBMS). Both supported MoO[subscript 3] catalysts show different levels of deoxygenation based on the cumulative biomass to MoO[subscript 3] mass ratio exposed to the catalytic bed. For biomass to MoO[subscript 3] mass ratios <1.5, predominantly olefinic and aromatic hydrocarbons are produced with no detectable oxygen-containing species. For ratios ≥1.5, partially deoxygenated species comprised of furans and phenols are observed, with a concomitant decrease of olefinic and aromatic hydrocarbons. For ratios ≥5, primary pyrolysis vapours break through the bed, indicating the onset of catalyst deactivation. Product quantification with a tandem micropyrolyzer–GCMS setup shows that fresh supported MoO[subscript 3] catalysts convert ca. 27 mol% of the original carbon into hydrocarbons comprised predominantly of aromatics (7 C%), olefins (18 C%) and paraffins (2 C%), comparable to the total hydrocarbon yield obtained with HZSM-5 operated under similar reaction conditions. Post-reaction XPS analysis on supported MoO[subscript 3]/ZrO[subscript 2] and MoO[subscript 3]/TiO[subscript 2] catalysts reveal that ca. 50% of Mo surface species exist in their partially reduced forms (i.e., Mo5[superscript +] and Mo3[superscript +]), and that catalyst deactivation is likely associated to coking.BP (Firm) (MIT Energy Initiative. Advanced Conversion Research Program)National Science Foundation (U.S.) (Award 1454299

Volcanic Ash Soils in Montana

Paper published as Bulletin 45 in the UM Bulletin Forestry Series.https://scholarworks.umt.edu/umforestrybulletin/1028/thumbnail.jp

Research Note, March 1981

This is issue 16: Soil Moisture and Temperature Regimes in Beaverhead County, Montanahttps://scholarworks.umt.edu/montana_forestry_notes/1014/thumbnail.jp

Quantification and Characterization of Aluminum Distributions in Commercial Beta and Mordenite Zeolites by Cobalt Exchange

The aluminum distribution throughout the zeolite framework determines the structural, ion-exchange and catalytic properties of the zeolite. Several methods have been proposed to control the Al distribution, but in order to accurately assess these methods a procedure is needed to quantify Al distribution in various zeolite frameworks. Co2+ ions exchange onto the zeolite framework at Al pairs, and atomic absorbance spectroscopy (AAS) can be used to quantify the number of exchanged Co2+ ions and, in turn, the overall number of Al pairs. Each framework exhibits differences in pore size and channel configuration which affect the equilibrium conditions needed for saturation of all paired Al sites with Co2+ ions. In order to achieve saturation of the Co2+ ions, a reproducible exchange procedure must be developed for each framework of interest. Commercial beta (BEA) and mordenite (MOR) zeolites were subjected to liquid-phase cobalt ion exchange with varying exchange solution molarity, temperature, number of repetitions and time of exchange. The zeolites were then washed and treated in an oxidizing environment at high temperatures before undergoing AAS analysis to determine Co2+ concentration and diffuse reflectance UV-Vis spectroscopy (DRUV-VIS) to ensure only bare Co2+ ions were present. The BEA framework was found to achieve saturation at the following conditions: 0.50 M Co(NO3)2 exchange solution, ambient temperature, 1 repetition and 12 hour exchange time. The exchange procedure for MOR zeolites requires a 0.05 M Co(NO3)2 solution, ambient temperature, 24 hour exchange time and 1 repetition. These procedures will aid in the creation of an accurate catalog of the Al distribution in various commercially available BEA and MOR zeolites, as well as aiding in further synthesis studies to control the Al distribution in BEA and MOR zeolites

Development and Characterization of a Table-Top Laser-Produced Plasma Source for In-Situ and Time-Resolved Soft X-Ray Absorption Spectroscopy

X-ray absorption spectroscopy (XAS) has emerged as an indispensable tool in the fields of carbon capture and conversion, providing element-specific insights into electronic structure, oxidation states, and chemical bonding. Of particular interest are soft X-rays (SXRs), which can probe the X-ray water window, enabling detailed studies of carbon, nitrogen, and transition metal L-edges in aqueous environments. Traditionally, access to this technique and this energy range has been limited to large- scale facilities like synchrotrons and XFELs, which can only serve a small population of users in a given year. Furthermore, more complex techniques such as time-resolved and in-situ XAS are practically inaccessible to the majority of users. This thesis explores the development of a table-top laser-produced plasma (LPP) source based on a gaseous target to extend the reach of XAS techniques into laboratory settings. Such sources offer significant advantages in accessibility, flexibility, and cost, while advances in X-ray optics and detection systems have further enhanced their utility. The research presented here focuses on the utilization of gaseous LPP sources for both in-situ and time-resolved XAS, pushing the boundaries of table-top soft X-ray absorption capabilities. Key achievements include exploration of the lower temporal limit of LPP sources for SXR emission, and the first demonstration of liquid-phase XAS measurements using a gaseous LPP source. Gas-phase measurements were also achieved using the system built in this work. Additionally, a novel UV-pump/SXR-probe technique was developed, enabling future time-resolved studies of charge transfer dynamics in transition metal oxides. These advances pave the way for detailed investigations of photodriven processes, interfaces, and catalytic mechanisms critical to carbon capture and conversion. By improving temporal resolution and expanding the scope of in-situ XAS techniques, this work addresses fundamental challenges in the field, bringing the power of synchrotron-like spectroscopy into everyday laboratories. Ultimately, the results presented here aim to democratize XAS, fostering a broader adoption of this technique in catalysis and materials research.</p

Montana Forestry Notes, June 1964

This is issue 1: Soil Temperatures in the Lubrecht Experimental Foresthttps://scholarworks.umt.edu/montana_forestry_notes/1000/thumbnail.jp

3-Hydr­oxy-7,8-dimethoxy­quinolin-2(1H)-one

In the crystal structure of the title compound, C11H11NO4, intra­molecular O—H⋯O hydrogen bonding results in the formation of a planar five-membered ring, which is nearly coplanar with the quinoline group. Inter­molecular N—H⋯O hydrogen bonds link the mol­ecules into centrosymmetric dimers

Furan Production from Glycoaldehyde over HZSM-5

Catalytic fast pyrolysis of biomass over zeolite catalysts results primarily in aromatic (e.g., benzene, toluene, xylene) and olefin products. However, furans are a higher value intermediate for their ability to be readily transformed into gasoline, diesel, and chemicals. Here we investigate possible mechanisms for the coupling of glycoaldehyde, a common product of cellulose pyrolysis, over HZSM-5 for the formation of furans. Experimental measurements of neat glycoaldehyde over a fixed bed of HZSM-5 confirm furans (e.g., furanone) are products of this reaction at temperatures below 300 °C with several aldol condensation products as coproducts (e.g., benzoquinone). However, under typical catalytic fast pyrolysis conditions (>400 °C), further reactions occur that lead to the usual aromatic product slate. ONIOM calculations were utilized to identify the pathway for glycoaldehyde coupling toward furanone and hydroxyfuranone products with dehydration reactions serving as the rate-determining steps with typical intrinsic reaction barriers of 40 kcal mol-1. The reaction mechanisms for glycoaldehyde will likely be similar to that of other small oxygenates such as acetaldehyde, lactaldehyde, and hydroxyacetone. This study provides a generalizable mechanism of oxygenate coupling and furan formation over zeolite catalysts