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Boron-containing materials such as hexagonal boron nitride, recently shown to be active and selective catalysts for the oxidative dehydrogenation of propane (ODHP), have been shown to undergo significant surface oxyfunctionalization and restructuring. Although experimental ex situ studies have probed the change in chemical environment on the surface, the structural evolution of it under varying reaction conditions has not been established. Herein we perform global optimization structural search with grand canonical genetic algorithm to explore the chemical space of off-stoichiometric restructuring of hexagonal boron nitride (hBN) surface under ambient as well as ODHP relevant reaction conditions. A grand canonical ensemble representation of the surface is established, and the predicted 11B solid-state NMR spectra are consistent with previous experimental reports. In addition, we investigated the relative sliding of hBN sheets and how it affects the surface chemistry with ab initio molecular dynamics simulations. The B-O linkages on the edges are found to be significantly strained during the sliding, causing the metastable sliding configurations to have higher reactivity towards activation of propane and water.

ispartof: ACS Catalysis vol:12 issue:15 pages:9559-9569 status: published

Titanium silicates of MWW structures with different Si/Ti ratios were prepared via hydrothermal synthesis using piperidine as the structure directing agent and boric acid as the crystallization agent. All the syntheses resulted in highly crystalline materials independent of the Si/Ti ratio. The observed morphology showed MWW-like well-defined thin hexagonal platelets. The synthesized Ti-MWW materials exhibited higher surface areas and partial meso-porosity compared to the commercial TS-1 catalyst. The coordination of the Ti-species was investigated by UV–vis- and IR-spectroscopy. The MWW titanium silicates were tested for the catalytic performance in the epoxidation of propylene in a laboratory-scale trickle bed reactor to compare their clear different physico-chemical properties with the commercial TS-1. The synthesized Ti-MWW materials showed significantly higher catalytic activities, up to 3.5 times, using acetonitrile as the solvent and enhanced epoxide selectivities partially up to 100% in methanol unlike TS-1. The effect of the Ti content in the MWW and the calcination conditions were investigated in propylene epoxidation, revealing the beneficial effect of a lower calcination temperature and an increased Ti content on the activity. The catalytic results were correlated with the physico-chemical properties of the synthesized materials. Graphical Abstract

Less than 10% of the plastics generated globally are recycled, while the rest are incinerated, accumulated in landfills, or leach into the environment. New technologies are emerging to chemically recycle waste plastics that are receiving tremendous interest from academia and industry. Chemists and chemical engineers need to understand the fundamentals of these technologies to design improved systems for chemical recycling and upcycling of waste plastics. In this paper, we review the entire life cycle of plastics and options for the management of plastic waste to address barriers to industrial chemical recycling and further provide perceptions on possible opportunities with such materials. Knowledge and insights to enhance plastic recycling beyond its current scale are provided. Outstanding research problems and where researchers in the field should focus their efforts in the future are also discussed.

Boron oxide/hydroxide supported on oxidized activated carbon (B/OAC) was shown to be an inexpensive catalyst for the oxidative dehydrogenation (ODH) of propane that offers activity and selectivity comparable to boron nitride. Here, we obtain an atomistic picture of the boron oxide/hydroxide layer in B/OAC by using 35.2 T

Boron oxide/hydroxide supported on oxidized activated carbon (B/OAC) was shown to be an inexpensive catalyst for the oxidative dehydrogenation (ODH) of propane that offers activity and selectivity comparable to boron nitride. Here, we obtain an atomistic picture of the boron oxide/hydroxide layer in B/OAC by using 35.2 T 11B and 17O solid-state NMR experiments. NMR spectra measured at 35.2 T resolve the boron and oxygen sites due to narrowing of the central-transition powder patterns. A 35.2 T 2D 11B{17O} dipolar heteronuclear correlation NMR spectrum revealed the structural connectivity between boron and oxygen atoms. The approach outlined here should be generally applicable to determine atomistic structures of heterogeneous catalysts containing quadrupolar nuclei. ispartof: Journal Of The American Chemical Society vol:144 issue:41 pages:18766-18771 ispartof: location:United States status: published

Potential active sites for the conversion of methane to methanol in Cu-exchanged SSZ-13 are identified using a combination of experimentally measured UV-vis-NIR spectroscopy and theoretical modeling.

A series of calcined MgAl mixed metal oxide catalysts with low Cu loadings (0.1 – 1.5 wt%) were tested for ethanol oligomerization to distillate-range molecules. The low Cu loading catalysts (0.1 – 0.6 wt%) had high selectivity to linear chain C4+ alcohols (49 – 63% selectivity) and C6+ esters (45 – 66% of total esters). More specifically, the diesel fuel precursor selectivities were over 75% for low Cu loading catalysts (0.1 – 0.6 wt%), with a decrease to 49% for a higher Cu loading catalyst (>1.2 wt% Cu) due to increased ethyl acetate and acetone formation. Alcohol and ester product selectivities follow a Schultz-Flory distribution. Alcohol selectivity was found to vary inversely with BET surface areas of the catalysts, whereas ester selectivity was found to increase with higher base site counts. However, Cu wt% loading was found to have a stronger impact in overall catalyst activity. The catalysts deactivated proportionally to the number of turnovers mainly due to coking, but could be regenerated by calcination.

Correction for ‘Expanding plastics recycling technologies: chemical aspects, technology status and challenges’ by Houqian Li et al., Green Chem., 2022, 24, 8899–9002, https://doi.org/10.1039/D2GC02588D.