Temperature-Pressure Swing Process for Reactive Carbon Capture and Conversion to Methanol: Techno-Economic Analysis and Life Cycle Assessment.

A model was developed to conduct techno-economic analysis (TEA) and life cycle assessment (LCA) for reactive carbon capture (RCC) and conversion of carbon dioxide (CO) to methanol. This RCC process is compared to a baseline commercialized flue gas CO hydrogenation process. An ASPEN model was combined with existing TEA and LCA models into a larger TEA/LCA framework in Python.

Multivariate Bayesian Optimization of CoO Nanoparticles for CO Hydrogenation Catalysis.

The hydrogenation of CO holds promise for transforming the production of renewable fuels and chemicals. However, the challenge lies in developing robust and selective catalysts for this process. Transition metal oxide catalysts, particularly cobalt oxide, have shown potential for CO hydrogenation, with performance heavily reliant on crystal phase and morphology.

The Overlooked Potential of Sulfated Zirconia: Reexamining Solid Superacidity Toward the Controlled Depolymerization of Polyolefins.

Closed-loop recycling via an efficient chemical process can help alleviate the global plastic waste crisis. However, conventional depolymerization methods for polyolefins, which compose more than 50% of plastics, demand high temperatures and pressures, employ precious noble metals, and/or yield complex mixtures of products limited to single-use fuels or oils. Superacidic forms of sulfated zirconia (SZrO) with Hammet Acidity Functions () ≤ - 12 (i.

Activating Molybdenum Carbide Nanoparticle Catalysts under Mild Conditions Using Thermally Labile Ligands.

Transition-metal carbides are promising low-cost materials for various catalytic transformations due to their multifunctionality and noble-metal-like behavior. Nanostructuring transition-metal carbides offers advantages resulting from the large surface-area-to-volume ratios inherent in colloidal nanoparticle catalysts; however, a barrier for their utilization is removal of the long-chain aliphatic ligands on their surface to access active sites. Annealing procedures to remove these ligands require temperatures greater than the catalyst synthesis and catalytic reaction temperatures and may further result in coking or particle sintering that can reduce catalytic performance.

Catalytic Activation of Polyethylene Model Compounds Over Metal-Exchanged Beta Zeolites.

Decomposition of polymers by heterogeneous catalysts presents a promising approach for reuse of waste plastics. We demonstrated non-hydrogenative decomposition of model polyolefins over proton-form and metal (Cu, Ni) ion-exchanged beta (BEA) zeolites at moderate temperatures (around 300 °C). Near complete polyolefin decomposition was observed in batch reactions monitored by thermogravimetric analysis, while decomposition at partial conversion was studied in flow reactions.

Electrocatalytic CO Reduction over CuP Nanoparticles Generated via a Molecular Precursor Route.

The design of nanoparticles (NPs) with tailored morphologies and finely tuned electronic and physical properties has become a key strategy for controlling selectivity and improving conversion efficiency in a variety of important electrocatalytic transformations. Transition metal phosphide NPs, in particular, have emerged as a versatile class of catalytic materials due to their multifunctional active sites and composition- and phase-dependent properties. Access to targeted transition metal phosphide NPs with controlled features is necessary to tune the catalytic activity.

Dehydrogenative Coupling of Methanol for the Gas-Phase, One-Step Synthesis of Dimethoxymethane over Supported Copper Catalysts.

Oxymethylene dimethyl ethers (OMEs), CH-(OCH)-OCH, = 1-5, possess attractive low-soot diesel fuel properties. Methanol is a key precursor in the production of OMEs, providing an opportunity to incorporate renewable carbon sources via gasification and methanol synthesis. The costly production of anhydrous formaldehyde in the typical process limits this option.

An Exceptionally Mild and Scalable Solution-Phase Synthesis of Molybdenum Carbide Nanoparticles for Thermocatalytic CO Hydrogenation.

Transition metal carbides (TMCs) have demonstrated outstanding potential for utilization in a wide range of catalytic applications because of their inherent multifunctionality and tunable composition. However, the harsh conditions required to prepare these materials have limited the scope of synthetic control over their physical properties. The development of low-temperature, carburization-free routes to prepare TMCs would unlock the versatility of this class of materials, enhance our understanding of their physical properties, and enable their cost-effective production at industrial scales.

Synthesis of α-MoC1-x Nanoparticles with a Surface-Modified SBA-15 Hard Template: Determination of Structure-Function Relationships in Acetic Acid Deoxygenation.

Surface modification of mesoporous SBA-15 silica generated a hydrophobic environment for a molybdenum diamine (Mo-diamine) precursor solution, enabling direct growth of isolated 1.9±0.4 nm α-MoC1-x nanoparticles (NPs) inside the pores of the support.

Femtosecond Measurements Of Size-Dependent Spin Crossover In Fe(II)(pyz)Pt(CN)4 Nanocrystals.

We report a femtosecond time-resolved spectroscopic study of size-dependent dynamics in nanocrystals (NCs) of Fe(pyz)Pt(CN)4. We observe that smaller NCs (123 or 78 nm cross section and <25 nm thickness) exhibit signatures of spin crossover (SCO) with time constants of ∼5-10 ps whereas larger NCs with 375 nm cross section and 43 nm thickness exhibit a weaker SCO signature accompanied by strong spectral shifting on a ∼20 ps time scale. For the small NCs, the fast dynamics appear to result from thermal promotion of residual low-spin states to high-spin states following nonradiative decay, and the size dependence is postulated to arise from differing high-spin vs low-spin fractions in domains residing in strained surface regions.

Structure-Function Relationships for Electrocatalytic Water Oxidation by Molecular [Mn12O12] Clusters.

A series of Mn12O12(OAc)(16-x)L(x)(H2O)4 molecular clusters (L = acetate, benzoate, benzenesulfonate, diphenylphosphonate, dichloroacetate) were electrocatalytically investigated as water oxidation electrocatalysts on a fluorine-doped tin oxide glass electrode. Four of the [Mn12O12] compounds demonstrated water oxidation activity at pH 7.0 at varying overpotentials (640-820 mV at 0.

Surface Chemistry Exchange of Alloyed Germanium Nanocrystals: A Pathway Toward Conductive Group IV Nanocrystal Films.

We present an expansion of the mixed-valence iodide reduction method for the synthesis of Ge nanocrystals (NCs) to incorporate low levels (∼1 mol %) of groups III, IV, and V elements to yield main-group element-alloyed Ge NCs (Ge1-xEx NCs). Nearly every main-group element (E) that surrounds Ge on the periodic table (Al, P, Ga, As, In, Sn, and Sb) may be incorporated into Ge1-xEx NCs with remarkably high E incorporation into the product (>45% of E added to the reaction). Importantly, surface chemistry modification via ligand exchange allowed conductive films of Ge1-xEx NCs to be prepared, which exhibit conductivities over large distances (25 μm) relevant to optoelectronic device development of group IV NC thin films.

Control of PbSe quantum dot surface chemistry and photophysics using an alkylselenide ligand.

We have synthesized alkylselenide reagents to replace the native oleate ligand on PbSe quantum dots (QDs) in order to investigate the effect of surface modification on their stoichiometry, photophysics, and air stability. The alkylselenide reagent removes all of the oleate on the QD surface and results in Se addition; however, complete Se enrichment does not occur, achieving a 53% decrease in the amount of excess Pb for 2 nm diameter QDs and a 23% decrease for 10 nm QDs. Our analysis suggests that the Se ligand preferentially binds to the {111} faces, which are more prevalent in smaller QDs.

Size and bandgap control in the solution-phase synthesis of near-infrared-emitting germanium nanocrystals.

We present a novel colloidal synthesis of alkyl-terminated Ge nanocrystals based on the reduction of GeI(4)/GeI(2) mixtures. The size of the nanocrystals (2.3-11.

Kinetics and mechanism of olefin epoxidation with aqueous H2O2 and a highly selective surface-modified TaSBA15 heterogeneous catalyst.

The reaction kinetics of cyclohexene epoxidation using aqueous H2O2 oxidant and the highly selective epoxidation catalyst Bu(cap)TaSBA15 were studied. The reaction was determined to be first-order in Ta(V) surface coverage. The reaction rate exhibited saturation with respect to increasing concentrations of cyclohexene and H2O2.

Highly selective olefin epoxidation with aqueous H2O2 over surface-modified TaSBA15 prepared via the TMP method.

Trialkylsiloxy-modified Ta(v) centers on mesoporous silica exhibit excellent selectivity for epoxide formation (>98% after 2 h) in the oxidation of cyclohexene using aqueous H2O2 as the oxidant; the modified catalysts exhibit an increased lifetime, retaining high selectivity after 6 h of reaction (>95% epoxide).

Influence of surface modification of Ti-SBA15 catalysts on the epoxidation mechanism for cyclohexene with aqueous hydrogen peroxide.

The thermolytic molecular precursor method was used to introduce site-isolated Ti(IV) centers onto the surface of a mesoporous SBA15 support. The resulting surface Si-OH/Ti-OH sites of the Ti-SBA15 catalysts were modified with a series of (N,N-dimethylamino)trialkylsilanes, Me(2)N-SiMe(2)(R) (where R = Me, (n)Bu, or (n)Oc). Compared with the unmodified catalysts, the surface-modified catalysts are more active in the oxidation of cyclohexene with H(2)O(2) and exhibit a significantly higher selectivity (up to 58%) for cyclohexene oxide formation (vs allylic oxidation products).

Determination of the active ingredient loperamide hydrochloride in pharmaceutical caplets by high performance thin layer chromatography with ultraviolet absorption densitometry of fluorescence quenched zones.

A quantitative method using silica gel HPTLC plates with fluorescent indicator, automated sample application, and automated UV absorption densitometry of the fluorescence quenching zones was developed and validated for determination of loperamide hydrochloride in anti-diarrheal medications. Samples of three brands of caplets assayed within 96.0-105% of the 2 mg label value.