The development of new heterogeneous catalytic processes for the production of ε-caprolactam

Ichihashi, Hiroshi; Satō, Hiroshi

doi:10.1016/s0926-860x(01)00887-0

Cited by 128 publications

(57 citation statements)

References 30 publications

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“…1 The presence of defective sites in their lattice can facilitate the formation of weak acidic centers (derived from silanol groups), which have been reported as active Beckmann rearrangement catalysts. [2][3][4] Although the amount of weak acid sites and, to some extent, the acidic strength of S-1 zeolite can be modulated by changing the crystallization conditions or through post-synthesis treatment, 2,5,6 its catalytic properties remain limited. In contrast, ZSM-5 is a strongly acidic zeolite that can catalyze several reactions, including olen oligomerization, aromatic alkylation, toluene disproportionation, methanol-to-hydrocarbon conversions (including MTG, MTO, MTP), and light hydrocarbon cracking and aromatization.…”

Section: Introductionmentioning

confidence: 99%

Silicalite-1 zeolite acidification by zinc modification and its catalytic properties for isobutane conversion

Liu

et al. 2018

RSC Adv.

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A series of Zn-modified Silicalite-1 (S-1) zeolites (Zn x /S-1) were prepared by the wetness-impregnation method and applied in the catalytic conversion of isobutane. The structure and location of Zn species in Zn x /S-1 were investigated using UV-Vis and N 2 physical adsorption. The acidity and origin of the acid sites in Zn x /S-1 were studied by NH 3 -temperature programmed desorption and Fourier-transform infrared analysis. The catalytic performance of Zn x /S-1 for isobutane conversion was investigated in a fixed-bed microreactor. In the experiments, the acidity of S-1 zeolite was dramatically increased by modification with Zn, with both Lewis and Brønsted sites identified in Zn x /S-1. The relationship between Brønsted acid sites and Zn-OH groups on ZnO clusters of Zn x /S-1 was also revealed for the first time.Furthermore, Zn x /S-1 catalysts exhibited excellent catalytic performances in both isobutane dehydrogenation and butene isomerization reactions. A high selectivity of total butene products ranging from 84.6 to 97.2 was achieved on the catalysts with different Zn loadings. Moreover, the linear correlation between isobutane conversion and the acid amount (determined by NH 3 -TPD) confirmed that the weak-to-medium acid sites in Zn x /S-1 should play a key role in isobutane conversion.

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Section: Introductionmentioning

confidence: 99%

Silicalite-1 zeolite acidification by zinc modification and its catalytic properties for isobutane conversion

Liu

et al. 2018

RSC Adv.

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“…5 shows the 29 Si MAS NMR spectra of the TS-1 samples before and after TEA treatment. A dominant uptake centered at -113 ± 1 ppm and a distinguishable shoulder at -103 ± 1 ppm can be identified, which are assigned to the Q 4 groups in Si(SiO) 4 and Q 3 groups of silicon-bearing OH groups, i.e., Si(OH)(SiO) 3 [60,61]. It can be seen that the intensity of the peak at -103 ppm decreases after TEA treatment, indicating that the amount of the silanol groups decreases.…”

Section: Resultsmentioning

confidence: 99%

“…This process has serious disadvantages because it involves several steps, requires abundant energy, uses many environmentally unfavorable chemicals and produces a large amount of ammonium sulfate as a by-product [3,4]. Hence, there is a growing incentive for the development of a new environmental friendly oxidation method.…”

Section: Introductionmentioning

confidence: 99%

Effect of triethylamine treatment of titanium silicalite-1 on cyclohexanone ammoximation in a continuous system

Zhang

Wang

et al. 2014

Reac Kinet Mech Cat

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TS-1 has been hydrothermally treated by aqueous solutions of triethylamine, characterized by a number of techniques and studied in the ammoximation of cyclohexanone with NH 3 and H 2 O 2 in a continuous system. Some irregular hollow cavities are created after the treatment by desilication. The catalytic activities of TS-1 are not affected, but the catalyst stabilities significantly increase after the treatment, which can be attributed to the generation of the cavities. The treatment conditions are optimized, with the catalyst stability being extended to ten times of the conventional TS-1. After the treatment, triethylamine can be separated simply through distillation and recycled. The causes of deactivation are elucidated to be the deposition of higher weight byproducts formed on the surface of the catalysts and the deactivated TS-1 can be effectively regenerated through calcination in air.

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“…The process starts with the TS-1 catalyzed ammoximation of cyclohexanone in NH 3 -H 2 O 2 followed by a Beckmann rearrangement carried out in the vapour phase over a high-silica MFI zeolite, another heterogeneous catalyst (Scheme 3.6) [29,30]. The use of zeolites in synthesis and in green chemistry is discussed in detail elsewhere [31,32].…”

Section: The Advantage Of Heterogeneous Catalysismentioning

confidence: 99%

The E Factor and Process Mass Intensity

Dicks

Hent

2014

SpringerBriefs in Molecular Science

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The environmental (E) factor and process mass intensity (PMI) metrics are introduced and thoroughly analyzed. As indispensable green metrics widely applied throughout the chemical industry, the E factor and PMI are calculated for numerous industrial processes throughout the chapter. A perspective on waste in the context of academic research, industrial synthesis and reactivity within alternative reaction media highlights the importance of material recovery, in particular with regard to reaction solvents. The section on catalysis further expands on the question of waste reduction by considering several important points. Advantages of heterogeneous catalysis which include catalyst recycling and simple product isolation and purification are described. Issues and potential solutions encountered with homogeneous catalysts and potential solutions are also discussed. Finally, the biocatalytic synthesis of pregabalin sheds light on the notions of solvent recovery and water intensity. Limitations of the E factor (which include failure to address the nature of the waste produced) provide for an introduction to process mass intensity. After explaining the simple relationship between PMI and E factor, the chapter turns to the benefits of PMI as a more robust front-end approach for evaluating the material efficiency of a process. This idea is captured by considering the biocatalytic synthesis of Singulair. defined as "anything that is not the desired product" [1], in the years following its conception, the E factor metric has contributed to significant industrial waste reduction [2][3][4][5]. In tandem with atom economy, the E factor has provided the global view of synthetic efficiency. Typical industrial E factors first published by Sheldon (Table 3.1) [1] have enhanced understanding about the problem of waste and enabled various solutions to address it. Modern techniques are now starting to show potential in bypassing certain synthetic limitations once perceived in Sheldon's original conclusions. In recent years, efforts toward waste reduction have enabled many innovations such that the majority of process chemists today consider determining an E factor as essential to process development [6]. Keywords Intrinsic and Global E FactorsThe E factor approach to waste complements the atom economy metric because it offers both intrinsic and global evaluations of a synthetic process. The intrinsic method is one which Andraos calls the environmental impact factor based on molecular weight (E mw ) [7]. This metric is calculated as the ratio of the molecular weight of all by-products divided by the molecular weight of the desired product. The E factor based on mass (E factor) offers a global perspective and is calculated as the ratio of the total mass of all waste to the mass of the desired product [1]. Figure 3.1 outlines the calculations for both metrics in the context of a balanced stoichiometric reaction. From the conservation of mass law it is possible to derive simple mathematical relationships between the E factor me...

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The development of new heterogeneous catalytic processes for the production of ε-caprolactam

Cited by 128 publications

References 30 publications

Silicalite-1 zeolite acidification by zinc modification and its catalytic properties for isobutane conversion

Silicalite-1 zeolite acidification by zinc modification and its catalytic properties for isobutane conversion

Effect of triethylamine treatment of titanium silicalite-1 on cyclohexanone ammoximation in a continuous system

The E Factor and Process Mass Intensity

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