http://scheikundeinbedrijf.nl/content/modules/modulenaam/files/b713736m.pdf

The E Factor: fifteen years on

E factors, green chemistry and catalysis: an odyssey

The role of pore-directing agents (PDAs) in the introduction of hierarchical porosity in silicalite-1 in alkaline medium was investigated. By incorporation of various PDAs in aqueous NaOH, homogenously distributed mesopores were introduced in 2.5 μm silicalite-1 crystals. It was proven for the first time that framework aluminum is not a prerequisite for the introduction of intracrystalline mesoporosity by desilication. The pore-directing role is not directly exerted by framework trivalent cations metals, but by species on the external surface of the zeolite. The inclusion of metal complexes (Al(OH)4−, Ga(OH)4−) and tetraalkyl ammonium cations (tetramethyl ammonium (TMA+), tetrapropyl ammonium (TPA+)) in the alkaline solution led to distinct mesopore surface areas (up to 286 m2 g−1) and pore sizes centered in the range of 5–20 nm. In the case alkaline treatment was performed in the presence of Al(OH)4−, all aluminum partially integrated in the zeolite giving rise to both Lewis and Bronsted acidity. Apart from the concentration and location, the affinity of the PDA to the zeolite surface plays a crucial role in the pore formation process. If the PDA is attracted too strongly (e.g., TMA+), the dissolution is reduced dramatically. When the pore-directing agent is not attracted to the zeolite’s external surface, excessive dissolution occurs (standard alkaline treatment). TPA+ proved to be the most effective PDA as its presence led to high mesopore surface areas (>200 m2 g−1) over a broad range of PDA concentrations (0.003–0.1 M). Importantly, our results enable to extend the suitability of desilication for controlled mesopore formation to all-silica zeolites.

Desilication mechanism revisited: highly mesoporous all-silica zeolites enabled through pore-directing agents.

In this study, we present a synthetic pathway for the fabrication of self-supporting zeolite monoliths consisting of crystallized nanoparticles. A resorcinol-formaldehyde-based organic aerogel is used as a template, and silicalite-1 is used as the zeolite example. The silicalite-1 monoliths obtained consist of individual well-defined zeolite nanocrystals with sizes of 30-40 nm. The monoliths exhibit a high mechanical stability and have hierarchical porosity, with micropores within the zeolite particles, a mesopore system formed by the packing of the nanoparticles, and a macropore system on the monolith level. Such monolithic zeolites show high selectivity typically above 80% to epsilon-caprolactam combined with a high rate of reaction of 0.46 g(caprolactame)/(g(catalyst).h) in the Beckmann rearrangement of cyclohexanone oxime.

Hierarchically structured monolithic silicalite-1 consisting of crystallized nanoparticles and its performance in the Beckmann rearrangement of cyclohexanone oxime.

Since it first appeared in literature in the early nineties, the Circular Economy (CE) has grown in significance amongst academic, policymaking, and industry groups. The latest developments in the CE field have included the interrogation of CE as a paradigm, and its relationship with sustainability and other concepts, including iterative definitions. Research has also identified a significant opportunity to apply circular approaches to our rapidly changing industrial system, including manufacturing processes and Industry 4.0 (I4.0) which, with data, is enabling the latest advances in digital technologies (DT). Research which fuses these two areas has not been extensively explored. This is the first paper to provide a synergistic and integrative CE-DT framework which offers directions for policymakers and guidance for future research through a review of the integrated fields of CE and I4.0. To achieve this, a Systematic Literature Review (SLR; n = 174) of the empirical literature related to digital technologies, I4.0, and circular approaches is conducted. The SLR is based on peer-reviewed articles published between 2000 and early 2018. This paper also summarizes the current trends in CE research related to manufacturing. The findings confirm that while CE research has been on the increase, research on digital technologies to enable a CE is still relatively untouched. While the “interdisciplinarity” of CE research is well-known, the findings reveal that a substantial percentage is engineering-focused. The paper concludes by proposing a synergistic and integrative CE-DT framework for future research developed from the gaps in the current research landscape.

https://www.mdpi.com/1996-1073/11/11/3009/pdf

Digitisation and the circular economy: A review of current research and future trends

Some aspects of the vapor phase Beckmann rearrangement for the production of ε-caprolactam over high silica MFI zeolites

Recently, Sumitomo Chemical Co., Ltd. developed the vapor-phase Beckmann rearrangement process for the production of e-caprolactam. In the process, cyclohexanone oxime is rearranged into e-caprolactam using a zeolite as a catalyst instead of sulfuric acid. EniChem in Italy developed the ammoximation process that involves the direct production of cyclohexanone oxime without producing any ammonium sulfate. Sumitomo Chemical Co., Ltd. has commercialized the combined process of vapor-phase Beckmann rearrangement and ammoximation in 2003. In this paper, the authors focus on some aspects of the vapor-phase Beckmann rearrangement catalysis. A solid catalyst that is mainly composed of a high-silica MFI zeolite (Silicalite-1) has been developed for the vapor-phase Beckmann rearrangement. This catalyst does not possess acidity that can be detected by ammonia TPD. Methanol fed into the reactor with cyclohexanone oxime improves the yield of caprolactam. Methanol reacts with terminal silanols on the zeolite surface and converts them to methoxyl groups. The modification of the catalyst by methanol has an important role for the Beckmann rearrangement reaction. Nest silanols located just inside the pore mouth of the MFI zeolite are supposed to be the active sites of the catalyst. We propose that the coordination between the NOH group of cyclohexanone oxime molecule and the nest silanols through hydrogen bonding is responsible for the reaction. The reaction mechanism of Beckmann rearrangement under vapor-phase conditions is the same as in the liquid phase, namely, the alkyl group in anti-position against the hydroxyl group of the oxime migrates to the nitrogen atom's position.

The Catalysis of Vapor-Phase Beckmann Rearrangement for the Production of ε-Caprolactam

e-caprolactam is produced by gas phase catalytic synthesis with high selectivity of lactam wherein cyclohexanone oxime is brought into contact with a crystalline metallo-silicate catalyst having Si/metal atomic ratio is more than 500. The metal moiety in the catalyst is Ga, Fe, B, Zr, Bi, Nb, Zn, Be, Cr, La, Ti, Hf, V and/or Cu.

Production of epsilon-caprolactam

In the production of e-caprolactam from cyclohexanon oxime in gaseous phase in the presence of solid catalysts, the catalysts, no matter whether they may have worked, are brought into contact with either aqueous solution of ammonium salts and at least one basic material or ammonia water.

Process for producing epsilon-caprolactam and activating solid catalysts therefor

e -Caprolactam is prepared by subjecting cyclohexanone oxime in a gas phase to a catalytic reaction using zeolite catalysts in the presence of water and at least one compound selected from alcohols and ether compounds.

Masaru Kitamura

Papers

Some aspects of the vapor phase Beckmann rearrangement for the production of ε-caprolactam over high silica MFI zeolites

The Catalysis of Vapor-Phase Beckmann Rearrangement for the Production of ε-Caprolactam

Production of epsilon-caprolactam

Process for producing epsilon-caprolactam and activating solid catalysts therefor

Process for producing epsilon-caprolactam by Beckmann-rearrangement in the gas phase in the presence of a zeolite catalyst and water