Dow Chemical (United States)

The conversion of CO2 into fuels and chemicals requires significant energy input to break C-O bonds and create C-C and C-H bonds. This review explores the energy and capital barriers to CO2 utilization, using ethylene production as a case study by comparing CO2 electroreduction with other carbon mitigation options, including carbon capture and sequestration. The world's energy and capital resources are limited-scarce, in the parlance of economics-and choosing to use them to implement one path to decarbonization displaces other options for decarbonization or other priorities. These opportunity costs are significant and should not be ignored. Instead of breaking the C-O bonds in CO2 to produce chemicals and fuels, society should prioritize the higher CO2 mitigation efficiencies of alternative approaches, such as carbon capture and sequestration, new process and catalyst technologies for key molecules, and capital-efficient hydrogen production.

Traditionally, hydrophobe-modified, water-soluble cellulose ethers are synthesized in a heterogeneous slurry process using ethylene oxide and long-chain alkyl halides or alkyl glycidyl ethers. In this work, water-soluble cellulose ethers were synthesized homogeneously from glycidyl reagents within a binary ionic liquid system in DMSO. The reaction solvent composition, temperature, and electrophile type were varied to understand the extent of etherification and the solubility of the cellulose ether products. A combination of the ionic liquids 1-ethyl-3-methyl imidazolium acetate (EmimAc) and chloride (EmimCl) resulted in the highest extent of etherification while maintaining an optically clear solution at 8.0 wt % cellulose; the reaction proceeded to completion in 30 min at 100 °C. Additionally, the dual role of weakly basic EmimAc as catalyst and solvent allowed for dissolution and modification of cellulose without the need for additional catalyst or acidic neutralization after the reaction. One-pot synthesis of hydrophobe-modified, water-soluble cellulose ethers exhibited a higher extent of etherification and higher efficiency than previously published heterogeneous reactions conducted with hydrophobic electrophiles of similar length. Rheological measurements of 3.0 wt % aqueous solutions of these cellulose ethers demonstrated a nearly four order-of-magnitude range of solution viscosity from 40 to 15,000 cP. Fully water-soluble cellulose ethers demonstrated an exponential dependence of solution viscosity on the degree of hydrophobe modification, allowing for tunability in a wide array of commercial products. This system demonstrates a versatile method for homogeneously synthesizing water-soluble, hydrophobically modified cellulose ethers in a single step.

A comprehensive analysis of the bioaccumulation of three cyclic (namely, D4, D5, and D6) and five linear (namely, L2, L3, L4, L5, and L6) volatile methylsiloxanes (VMS) in biota was conducted by reviewing 50 published articles and laboratory reports on aquatic (82%) and terrestrial species (18%). A total of 178 bioaccumulation values were evaluated employing a quantitative weight-of-evidence (qWoE) approach provided by the Bioaccumulation Assessment Tool. Considerable variability of bioconcentration factor (BCF) and bioaccumulation factor (BAF) values was observed for VMS in aquatic organisms, which ranged from below to above their respective regulatory threshold values. The frequency of evidence for non-bioaccumulation (ie, BCF or BAF <2000) was ≥50% for D6, L2, L5, and L6. Conversely, laboratory biomagnification factor (BMF) values were generally (≥71%) less than 1, indicating low bioaccumulation potential through dietary uptake. Field BMFs displayed more variability but still suggested a low bioaccumulation potential. Despite the majority (≥65%) of trophic magnification factors (TMFs) in aquatic food webs being below 1, the broad range of TMF values for all VMS examined indicates potential uncertainties introduced by environmental factors in the target environments (e.g., chemical exposure gradient) and sampling bias. Overall, lines of evidence (≥71%) suggest that cyclic and linear VMS generally do not bioaccumulate in aquatic species, with dietary uptake being the primary pathway. For terrestrial species, primarily rats, predicted and field BMFs were less than 1 at 37 °C, primarily via respiratory elimination. Field TMFs for terrestrial food webs, including invertebrates and various bird species with body temperatures of 18 and 40 °C, respectively, were sourced from a single study, where D4 demonstrated trophic dilution, while D5 and D6 generally did not biomagnify in this terrestrial food web.

Abstract “Sorp‐vection” is a membrane separation technique that synergistically combines sorption with convective flow mechanisms. Beyond its conceptual discussion, we demonstrate a sorp‐vection separation achieved in a gas–liquid system, where permeation of a gas directly drives selective permeation of an organic solute across a dense polymer layer overcoming osmotic limitations of conventional membrane processes. Here, a long‐standing challenge in silicone oil production is addressed, in which residual cyclic oligosiloxanes are removed from silicone oil streams through permeation of CO 2 across an optimally crosslinked PDMS selective layer. A lab‐scale 1 st generation Sorp‐vection system demonstrated, with a separation factor above 15 to remove D4 (octamethylcyclotetrasiloxane) from low‐concentration feeds using both lab‐grade silicone oil (Sigma‐Aldrich) and an industrial‐grade feed (DOW‐SFD). Good agreement was found with a predictive model based on liquid D4 and high‐molecular‐weight silicone oil sorption data in crosslinked PDMS. This proof‐of‐concept study introduces the sorp‐vection strategy, expanding it from conventional two‐component systems to a three‐component configuration in which convective flow is introduced as an independent driving entity. Addressing concentration polarization in next‐generation versions of the sorp‐vection process is expected to ensure stable long‐term performance and to establish sorp‐vection as a transformative approach for industrial purification.

“Sorp‐vection” is a membrane separation technique that synergistically combines sorption with convective flow mechanisms. Beyond its conceptual discussion, we demonstrate a sorp‐vection separation achieved in a gas–liquid system, where permeation of a gas directly drives selective permeation of an organic solute across a dense polymer layer overcoming osmotic limitations of conventional membrane processes. Here, a long‐standing challenge in silicone oil production is addressed, in which residual cyclic oligosiloxanes are removed from silicone oil streams through permeation of CO2 across an optimally crosslinked PDMS selective layer. A lab‐scale 1st generation Sorp‐vection system demonstrated, with a separation factor above 15 to remove D4 (octamethylcyclotetrasiloxane) from low‐concentration feeds using both lab‐grade silicone oil (Sigma‐Aldrich) and an industrial‐grade feed (DOW‐SFD). Good agreement was found with a predictive model based on liquid D4 and high‐molecular‐weight silicone oil sorption data in crosslinked PDMS. This proof‐of‐concept study introduces the sorp‐vection strategy, expanding it from conventional two‐component systems to a three‐component configuration in which convective flow is introduced as an independent driving entity. Addressing concentration polarization in next‐generation versions of the sorp‐vection process is expected to ensure stable long‐term performance and to establish sorp‐vection as a transformative approach for industrial purification.

Styrene (S)/2-ethylhexyl acrylate (EHA) random copolymers (p(S/EHA)) were previously reported to exhibit remarkable glass transition breadth (Tg breadth or ΔTg) and facile self-healing over a broad composition range. Here, we investigate whether similar effects can be achieved with other commercially relevant monomers in place of styrene. Three methacrylates were employed: methyl methacrylate (MMA), ethyl methacrylate (EMA), and n-butyl methacrylate (BMA). The methacrylate homopolymers exhibited ΔTg values several times that of polystyrene and exceeded the maximum ΔTg of p(S/EHA). The p(MMA/EHA) copolymers showed increasing ΔTg with increasing EHA content. In contrast, p(EMA/EHA) copolymers showed an invariance in ΔTg compared to PEMA, and p(BMA/EHA) copolymers showed decreasing ΔTg with increasing EHA. Copolymers of n-hexyl acrylate (nHA) with each methacrylate were also prepared. The incorporation of nHA into MMA and EMA copolymers led to little or no ΔTg enhancement, whereas p(BMA/nHA) copolymers exhibited decreasing ΔTg with increasing nHA. Both p(MMA/EHA) and p(BMA/EHA) copolymers exhibited generally larger ΔTg than the corresponding p(MMA/nHA) and p(BMA/nHA) systems. All tested methacrylate-based copolymers except for one, p(BMA/EHA) with 31 mol% EHA content, demonstrated “grudgingly” slow or incomplete, room-temperature self-healing over 100 h. These findings highlight the comonomer-dependent nature of ΔTg and self-healing when EHA is incorporated with methacrylates.

This Letter describes the photocatalytic C(sp2)-H amination of electron-rich arenes with azoles via an electron donor-acceptor (EDA) pathway. The acceptor in this system is proposed to be a pyridin-1-ium salt generated in situ from the combination of pyridine and either LiOTf or HOTf. The reactions proceed with irradiation using 370 nm LEDs, and the pyridine/acid acceptor can serve as a catalyst under aerobic conditions. This represents a rare example of a catalytic acceptor in EDA photochemistry.