Chemoselective nitrilation of dimethyl adipate with ammonia over carbon encapsulated WO_x catalysts under continuous flow conditions

Abstract

Adiponitrile (ADN) is a key intermediate for the industrial production of polyamide represented by nylon 66. In this study, the chemoselective nitrilation of dimethyl adipate (DMA) with ammonia (NH3) under...

Synthesis of adiponitrile from dimethyl adipate and ammonia in the vapor-phase over niobium oxide

“…Thus, a parallel study focusing on regulating the oxygen-deficient WO x structure to reach a high reactivity was conducted in our lab. 34 To our delight, the observed reactivity of Nb 2 O 5 is both efficient (C DMA : 66.5%) and nitrile selective (S ADN+MCP : 83.9%). On the other hand, the reactivity over amphoteric metal oxides, such as ZnO, Al 2 O 3 , Fe 2 O 3 and CeO 2 , is comparable, while the desired S ADN+MCP for most cases is very poor.…”

Adjustment of W–O–Zr Boundaries Boosts Efficient Nitrilation of Dimethyl Adipate with Ammonia on WOx/ZrO2 Catalysts

“…In combination with the overall selectivity of nitrilation ( S ADN+MCP ), the best performance was achieved at 2.4 atoms·nm –2 featured for WO x (2.0)/ZrO 2 , wherein WO x -species was present on the surface of ZrO 2 as medium oligomerized polytungstate (∼2D WO x species). As compared with that of previous WO x @C/C catalysts under overestimation, the TOF value of WO x /ZrO 2 increases exponentially (for the data of comparison, see Table S7).…”

“…The nitrilation of DMA to ADN with NH 3 was determined as a tandem reaction by taking MCP as the intermediate, , as shown in Figure a. Herein, the performance of WO x (m)/ZrO 2 (m = 0, 1.0, 1.5, 2.0, 2.5, 3.0, 5.0, 10.0, and 20.0) and WO 3 was evaluated at 350 °C with a NH 3 /DMA molar ratio of 8.0 and a WHSV DMA of 1.6 h –1 (Figure b and the corresponding data listed in Table S3).…”

“…The hydrocyanation of butadiene accounts for the most efficient route, leading to ADN, of which the market share records about 65%. , The rest two pilot routes include electrolytic dimerization of acrylonitrile , and ammoniation of adipic acid with ammonia (NH 3 ) . During the past decades, significant efforts have been dedicated to developing novel routes with attempts to address the issues suffered by the existing production technology, including either the toxicity of raw materials or high energy consumption. − In this domain, China TianChen Engineering Corporation Ltd. and we independently reported the direct transformation of dimethyl adipate (DMA) to ADN by patents. , Further details of such a protocol were obtained from the recent two reports by our group, , wherein WO 3 displays excellent nitrile selectivity but low single-pass conversion. It thus partially terminates at the intermediate product of methyl 5-cyanopentanoate (MCP), corresponding to the feature of a tandem reaction .…”

“…14 Meanwhile, only a few improvements were made in the reactivity by fabricating the catalyst from carbon-encapsulated oxygen-deficient WO x<3 . 15 In fact, the gas-phase nitrilation of carboxylic monoesters with NH 3 catalyzed by non-noble metal oxides received much attention, considering both the availability of raw materials and the environmental benignity of the process. 16−18 For instance, Auroux's group examined the performance of various acidic, amphoteric, and basic solids on the direct nitrilation of lauric acid methyl ester with NH 3 in a gas-phase continuous downstream process at 300 °C, 16 wherein ester aminolysis was determined as the rate-limiting step and the conversion was controlled by the volumetric density of medium-strength acid sites.…”