Hierarchical Zr‐MTW Zeolites Doped with Copper as Catalysts of Ethanol Conversion into 1,3‐Butadiene

Abstract

The hierarchical Zr-MTW zeolites are prepared using NH 4 F and HF as mineralizing agents and structure-directed agent like Gemini-type surfactant and studied by X-ray diffraction (XRD), 29 Si magic angle spinning nuclear magnetic resonance ( 29 Si MAS NMR), Fourier transform infrared (FTIR) spectroscopy with pyridine, 2,6-di-tert-butylpyridine and CD 3 CN as probe molecules. Structural characteristics and acid-base properties of the zeolites depend on concentration of fluorine precursor in the reaction medium (a ratio of Si/F). The hierarchical Zr-MTW zeolites (included doped with copper) have been tested in ethanol conversion into 1,3-butadiene by Lebedev method. The symbatical dependence of 1,3-butadiene productivity with the concentration of Lewis acidic sites determined by FTIR spectroscopy of adsorbed CD 3 CN is observed. 1.3-Butadiene selectivity of 68 % with ethanol conversion of 81 % are achieved in the presence of Cu/Zr-MTW catalyst. [a] M. M. Kurmach, Dr. O. V. Larina, Dr. P. I. Kyriienko, P. S. Yaremov, Dr. O. V. Shvets, Prof. S. O. Soloviev alexshvets@ukr.net [b] Dr.

Properties and activity of Zn–Ta-TUD-1 in the Lebedev process

“…Kyriienko et al also reported a direct relationship between butadiene productivity and the relative amount of Lewis acid sites probed by CDCl 3 on Cu-doped Zr-containing zeolites. 26 Similar correlations have yet to be established on other materials, but there is strong evidence that Lewis acidity plays a role in other catalytic systems. 27 Another crucial component of catalysts active in the Lebedev process is their ability to convert ethanol to acetaldehyde.…”

Ethanol-to-butadiene: the reaction and its catalysts

“…207 Tetrahedral hafnium, niobium and tantalum oxides sites are also known to form when dispersed on catalysts carriers, but can adopt different structures when in bulk. [219][220][221][222][223][224] Linear correlations between the acidity and catalytic activity with different catalysts were observed by other scholars: Kyriienko et al reported a correlation between the relative concentration of Lewis acid sites in Zr-MTW catalysts determined by FTIR spectroscopy of adsorbed CD 3 CN and butadiene productivity; 225 the present authors reported a direct correlation between the number of acid sites probed in Zn-Ta catalysts by NH 3 and the selectivity towards butadiene. 103 Contrarily, Dagle et al, who quantified the Lewis acid sites of Ag/ZrO 2 /SiO 2 catalysts with FTIR spectroscopy of pyridine, found that excessive Lewis acid site concentration caused by modifying the ZrO 2 loading lowered both butadiene selectivity and productivity in favor of ethanol dehydration products (Fig.…”

“…Kyriienko et al prepared a hierarchical copper-doped Zr-MTW zeolite as a catalyst for the Lebedev process. 225 It was found that the nature and concentration of fluoride-containing mineralizing agents used during synthesis influenced the morphological characteristics, acid-base properties and catalytic activity in the Lebedev process. Better catalytic performances were obtained with HF and a Si : F ratio of 4, affording a butadiene selectivity of 68% and an ethanol conversion of 81% (Table 4, entry 22).…”

Recent Advances in Catalysts for the Conversion of Ethanol to Butadiene

“…Recently, a number of well-ordered 2D and 3D supports have been investigated for the ETB process (Table 4). [29,98,[100][101][102][103][104][105][106][107][108][109][110][111][112][113][114][115][116] Chae et al investigated the influence of the type of mesostructure, pore size and particle morphology of silicasupported Ta catalysts for BD production from ethanol and acetaldehyde. [100] The ordered mesoporous silicas (OMS), SBA-15 which has hexagonal pores in a 2D array with long 1D channels (pore diameters of 4.6-10.9 nm), KIT-6 with a bicontinuous cubic structure (pore diameter 7.9 nm) and MCM-41-type MMS with smaller 2D hexagonal pores (2.5 nm) were used as supports and loaded with 2 wt.% Ta.…”

“…For example, hierarchical Zr and Cu promoted MTW (ZSM-12; a high-silica zeolite with a 1-D pore system of straight channels formed from 12-membered rings) gave 55% BD yield at WHSV of 0.5 h À 1 . [109] Zeolite beta is used in a number of studies. This zeolite has a 3D pore system of intersecting channels formed by 12-membered rings and pore channels of 0.67 nm diameter.…”