Techno-Economic Analysis of Glycerol Valorization via Catalytic Applications of Sulphonic Acid-Functionalized Copolymer Beads

MOF-808 as an Efficient Catalyst for Valorization of Biodiesel Waste Production: Glycerol Acetalization

Glycerol is the main residue in the biodiesel production industry; therefore, their valorization is crucial. The acetalization of glycerol toward fuel additives such as solketal (2,2-dimethyl-1,3-dioxolan-4-methanol) is of high interest, promoting circular economy since it can be added to biodiesel or even fossil diesel to improve their quality and efficiency. Straightforward-prepared metal-organic framework (MOF) materials of the MOF-808 family were applied to the valorization of glycerol for the first time. In particular, MOF-808(Hf) was revealed to be an effective heterogeneous catalyst to produce solketal under moderate conditions: a small amount of the MOF material (only 4 wt% of glycerol), a 1:6 ratio of glycerol/acetone, and a temperature of 333 K. The high efficiency of MOF-808(Hf) was associated with the high amount of acid centers present in its structure. Furthermore, its structural characteristics, such as window opening cavity size and pore diameters, were shown to be ideal for reusing this material for at least ten consecutive reaction cycles without losing activity (conversion > 90% and selectivity > 98%). Remarkably, it was not necessary to wash or activate the MOF-808(Hf) catalyst between cycles (no pore blockage occurred), and it maintained structural integrity after ten cycles, confirming its ability to be a sustainable heterogeneous catalyst for glycerol valorization.

Techno-Economic Assessment and Sensitivity Analysis of Glycerol Valorization to Biofuel Additives via Esterification

Glycerol is a valuable feedstock, produced in biorefineries as a byproduct of biodiesel production. Esterification of glycerol with acetic acid yields a mixture of mono-, di-, and triacetins. The acetins are commercially important value-added products with a wide range of industrial applications as fuel additives and fine chemicals. Esterification of glycerol to acetins substantially increases the environmental sustainability and economic viability of the biorefinery concept. Among the acetins, diacetin (DA) and triacetin (TA) are considered high-energy-density fuel additives. Herein, we have studied the economic feasibility of a facility producing DA and TA by a two-stage process using 100,000 tons of glycerol per year using Aspen Plus. The capital costs were estimated by Aspen Process Economic Analyzer software. The analysis indicates that the capital costs are 71 M$, while the operating costs are 303 M$/year. The gross profit is 60.5 M$/year, while the NPV of the project is 235 M$ with a payback period of 1.7 years. Sensitivity analysis has indicated that the product price has the most impact on the NPV.

Nuclear-driven production of renewable fuel additives from waste organics

Non-intermittent, low-carbon energy from nuclear or biofuels is integral to many strategies to achieve Carbon Budget Reduction targets. However, nuclear plants have high, upfront costs and biodiesel manufacture produces waste glycerol with few secondary uses. Combining these technologies, to precipitate valuable feedstocks from waste glycerol using ionizing radiation, could diversify nuclear energy use whilst valorizing biodiesel waste. Here, we demonstrate solketal (2,2-dimethyl-1,3-dioxolane-4-yl) and acetol (1-hydroxypropan-2-one) production is enhanced in selected aqueous glycerol-acetone mixtures with γ radiation with yields of 1.5 ± 0.2 µmol J^-1 and 1.8 ± 0.2 µmol J^-1, respectively. This is consistent with the generation of either the stabilized, protonated glycerol cation (CH₂OH-CHOH-CH₂OH₂⁺) from the direct action of glycerol, or the hydronium species, H₃O⁺, via water radiolysis, and their role in the subsequent acid-catalyzed mechanisms for acetol and solketal production. Scaled to a hypothetically compatible range of nuclear facilities in Europe (i.e., contemporary Pressurised Water Reactor designs or spent nuclear fuel stores), we estimate annual solketal production at approximately (1.0 ± 0.1) × 10⁴ t year^-1. Given a forecast increase of 5% to 20% v/v% in the renewable proportion of commercial petroleum blends by 2030, nuclear-driven, biomass-derived solketal could contribute towards net-zero emissions targets, combining low-carbon co-generation and co-production.

Facile and Mild Access to Fluorescent Ladder-Type Indolo[3,2-a]carbazoles via Cascade Annulation

A set of fluorescent ladder-type indolo[3,2-a]carbazoles were rationally developed via cascade annulation of indoles and nitroolefins under mild reaction conditions. Diverse functional groups were tolerated. Moreover, structure–photophysical properties relationships (SPPR) of indolo[3,2-a]carbazoles were observed to be simply tuned by changing the electronic nature of the peripheral substituents.

Efficiently diastereoselective synthesis of functionalized hydro-carbazoles by base-mediated tandem annulation of 1-(2-amino-aryl)prop-2-en-1-ones and sulfur ylide

The base-promoted [3 + 3]/[1 + 4] tandem reaction of tosyl-protected o-amino α,β-unsaturated ketones and crotonate-derived sulfur ylide is developed for efficiently diastereoselective synthesis of functionalized hydrocarbazoles.