Fundamental roles of ZnO and ZrO 2 in the conversion of ethanol to 1,3-butadiene over ZnO–ZrO 2 /SiO 2

ACS Sustainable Chem. Eng.

Guo

Gao

et al. 2021

The direct conversion of ethanol to butadiene (ETB) is a promising approach for renewable butadiene production. However, simultaneous achievement of high butadiene selectivity and catalyst stability has always been a challenge. Here, the multifunctional ZnZrTUD-1 catalyst possesses both superior catalytic performance and stability in direct ETB conversion. To study the effect of the active centers of catalysts on the catalytic performance, the designed active centers of the catalysts were optimized and further characterized by multiple techniques. One-pot hydrothermal synthesis was utilized to improve the interaction among ZnO, ZrO2, and TUD-1 mesoporous silicate. The results demonstrated that the optimized ZnZrTUD-1 catalyst possessed an excellent ability of resistance to carbon deposition and exhibited a synergistic catalysis effect. When the reaction was conducted at 400 °C and a weight hourly space velocity of 0.38 h–1, the catalytic performance revealed that it generated an outstanding butadiene selectivity of 62.5% and an ethanol conversion of 84.6%, which still remained stable during 50 h on stream.

Section: Resultsmentioning

confidence: 99%

Section: Table 1 Textural Properties Of the Synthesized Catalystsmentioning

confidence: 99%

One-Pot Hydrothermal Synthesis of Multifunctional ZnZrTUD-1 Catalysts for Highly Efficient Direct Synthesis of Butadiene from Ethanol

ACS Sustainable Chem. Eng.

Guo

Gao

et al. 2021

ACS Sustainable Chem. Eng.

“…This assumption is consistent with the results of FTIR spectroscopic measurements of adsorbed pyridine (Figure ): at 523 K, the intensity of the bands corresponding to Lewis acid sites is higher for ZnLa–Zr 1 SiBEA than for ZnLa–Zr 3 SiBEA. Moreover, ethanol conversion with the formation of C 4 products is known to occur in the presence of ZrO 2 /SiO 2 systems , and individual ZrO 2 . − According to ref , oxygen vacancies and coordinatively unsaturated Zr 4+ ions are active sites of ethanol conversion into AA. The formation of subnanoclusters with an increase in the heteroelement content in dealuminated BEA zeolite involves a decrease in ethanol–acetaldehyde mixture conversion (without a decrease in 1,3-BD selectivity) as was previously observed for Nb-containing catalysts …”

Section: Resultsmentioning

confidence: 99%

“…This assumption is consistent with the results of FTIR spectroscopic measurements of adsorbed pyridine (Figure 2): at 523 K, the intensity of the bands corresponding to Lewis acid sites is higher for ZnLa− Zr 1 SiBEA than for ZnLa−Zr 3 SiBEA. Moreover, ethanol conversion with the formation of C 4 products is known to occur in the presence of ZrO 2 /SiO 2 systems 16,45 and individual ZrO 2 . 46−49 According to ref 49, oxygen vacancies and coordinatively unsaturated Zr 4+ ions are active sites of ethanol conversion into AA.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Design of Effective Catalysts Based on ZnLaZrSi Oxide Systems for Obtaining 1,3-Butadiene from Aqueous Ethanol

Larina

Shcherban

Kyriienko

et al. 2020

ZnLaZrSi oxide systems prepared with a silica component of the different nature have been studied in 1,3-butadiene production from aqueous ethanol. The following silica materials were used: KSKG, A-175, A-380, SBA-15, MCM-41, MCM-48, MCF and dealuminated BEA zeolites. The characteristics of the porous structure of the silica support, such as porosity, pore size distribution, specific and external surface areas, were found not to be critical parameters for achieving a high 1,3-butadiene yield during the EtOH-H 2 O mixture conversion in the presence of ZnLaZrSi oxide catalysts. On the contrary, the quantity and strength of Lewis acid sites, which in turn differ depending on the choice of silica material, have a significant impact on 1,3-butadiene selectivity and yield. The highest values of the selectivity of 1,3-butadiene formation (up to 68 %) and yield as well as stability toward deactivation in the presence of H 2 O were achieved over ZnLaZr-KSKG, ZnLaZr-SBA-15 and ZnLa-Zr 1 SiBEA (with mononuclear isolated tetrahedral Zr(IV) species). The productivity of ZnLa-Zr 1 SiBEA catalyst accounts for 0.324 g 1,3-BD •g cat -1 •h -1 (T = 648К, WHSV = 2.88 h -1 , 80 vol% EtOH in water as an EtOH source). The main reason for the decrease in 1,3-butadiene yield in the presence of H 2 O in the reaction mixture was shown to be a deactivation of acetaldehyde condensation sites on the catalyst surface, while the rate of acetaldehyde formation decreases slightly. According to 1 H-13 C CP/MAS NMR spectroscopic results, the use of aqueous ethanol as the feed for ETB-process is very advantage to prevent the carburization of the catalysts.= 2.88 h -1 , 80 vol% EtOH in water as an EtOH source). Therefore, for industrial realization of ETB process the development of the effective catalysts based on dealuminated BEA zeolites is also promising. ASSOCIATED CONTENTSupporting Information. The following file is available free of charge. 29Si and 1 H -29 Si CP MAS NMR spectra of ZnLa-Zr 3 SiBEA sample, SEM images of the ZnLaZrSi samples at three magnifications, the indices of EtOH-water mixture conversion in the presence of ZnLaZrSi oxide systems, the indices of ETB process in the presence of 2 %ZnO/6 %ZrO 2 -KSKG (DOCX).

“…This result further indicated that Zn species promoted the coordination of Zr species to form more acid sites, and Zr species inhibited the interaction between Zn species and silanol to exist in the form of ZnO, which was beneficial to the dehydrogenation of ethanol to improve BD production. 62 In Fig. S7, † pure Si-beta, ZnO, and ZrO 2 exhibited low acid properties.…”

Section: Acid-base Propertiesmentioning

confidence: 99%

Selective direct conversion of aqueous ethanol into butadiene via rational design of multifunctional catalysts

Peng

et al. 2022

Catal. Sci. Technol.