C:Corrosive;
79-10-7Relevant articles and documents
Acetylene carbonylation over Ni-containing catalysts: Role of surface structure and active site distribution
Xie, Hao,Lin, Tiejun,Shi, Li,Meng, Xuan
, p. 97285 - 97292 (2016)
Heterogenization of homogeneous catalyst for acetylene carbonylation was carried out by preparing a series of Ni-modified catalysts (Ni-ZSM-5, Ni-IM-5 and Ni-MCM-41). Several important properties of the heterogeneous catalysts were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES), XPS, XRD, N2 adsorption, pyridine-FTIR, SEM and TGA. Moreover, we used various activity criteria to dissipate perturbing factors, when we focused on the influence of surface structure and active site distribution. The result that Ni-IM-5 had the greatest TOFNi = 5107 g acrylic acid per g Ni per h showed that the surface structure of samples did not influence the catalyst performance significantly. In addition, the highest ratio of nickel sites/acid sites in Ni-MCM-41 represented the best active site distribution. Thus, Ni-MCM-41 has the highest TOFcat = 70.6 g acrylic acid per g cat. per h. Furthermore, stability testing of the catalysts showed the Ni-MCM-41 could be used four times, while others only twice.
A unique nickel-base nitrogen-oxygen bidentate ligand catalyst for carbonylation of acetylene to acrylic acid
Cui, Long,Yang, Xiangui,Zeng, Yi,Chen, Yuntang,Wang, Gongying
, p. 57 - 61 (2019)
A nickel-base nitrogen-oxygen bidentate ligand catalyst was prepared in-situ via the complexation method. Our results show that the ligand with nickel can form a chelate catalyst possessing a ring structure, which exhibits good catalytic performance in the carbonylation reaction of acetylene to acrylic acid (AA). Furthermore, we discovered that, under our optimized conditions, when 8-hydroxyquinoline (HQ) is used as the ligand [c(Ni(OAc)2·4H2O) = 15 × 10?6 mol L?1, n(HQ):n(Ni(OAc)2·4H2O) = 1:1, V(H2O) = 7 mL], 70.1% conversion of acetylene and 92.4% the selectivity of AA is achieved at 200 °C with 8.0 MPa pressure for 30 min. Compared to traditional acetylene carbonylation catalysts and nickel-base phosphine ligand homogeneous complex catalysts, our catalytic system has unique advantages, including no copper, no halogen and no carbon deposition generated during the reaction process. It displays high selectivity and no corrosion of equipment, suggesting that this catalytic system possesses future industrial applications.
Ni-exchanged Y-zeolite: An efficient heterogeneous catalyst for acetylene hydrocarboxylation
Lin, Tie Jun,Meng, Xuan,Shi, Li
, p. 163 - 171 (2014)
A series of Ni-modified Y-zeolites with varying Ni loading in the presence of cupric salt as promoter were studied for acetylene hydrocarboxylation performed in a batch reactor. The catalysts were characterized by elemental analysis, H2-TPR, XRD, NH3-TPD, pyridine-FTIR, SEM, TG-DTG and Raman. It was found that the catalytic activity showed a pronounced dependence on the supports, metal introduction method, promoters and reaction conditions. The nickel species present as charge compensation cations in the zeolite framework constitute the active sites, and the acid sites help to promote the performance of carbonylation. Moreover, two types of coke were observed, and the remarkable reusability of NiY is attributable to the location of the coke outside the zeolite crystals. High catalytic performance was obtained over a NiY(7.0) catalyst with 62 gacrylic acid/(g cat. · h) of yield at 235 °C, 3.6 MPa of initial total pressure and 0.8 mM/l of cupric bromide within 40 min of reaction time. This is the most effective heterogeneous system for synthesizing acrylic acid by carbonylation of acetylene to date.
Exploring the multifunctionality and accessibility of vanadosilicates to produce acrylic acid in one-pot glycerol oxydehydration
Jones, Christopher W.,Lopez-Castillo, Alejandro,Martins, Leandro,Vieira, Luiz H.
, (2020)
Acrylic acid is one of the most attractive products directly produced from glycerol, and many efforts are still made to thoroughly understand the role of different catalytic sites in the reaction. In this work, we prepared Al-free vanadosilicates presenting structures analog to ferrierite and ITQ-6 zeolites (2D and 3D structures). The materials were efficient in catalyzing the one-pot conversion of glycerol to acrylic acid. The different vanadium species in the catalysts had specific roles in each step of the reaction. By exposing samples to humid conditions, dissociative adsorption of water produced hydroxylated sites (O3V-OH-Si) that acted as extrinsic Br?nsted acid sites. The deprotonation energy of these sites was estimated by DFT calculations and found to be close to deprotonation energy of intrinsic Br?nsted acidity of aluminosilicates with the same zeolitic structure, indicating the ability of the active site to dehydrate glycerol to acrolein. The formation of these sites seems to effectively block potential Lewis acidity of the vanadosilicates since acetol, a dehydration side product, was not formed. Spectroscopic data showed changes in oxidation states of vanadium in these sites after the reaction, presenting V5+ and V4+ states, indicating the activity of these sites on the oxidation step during oxidation of acrolein to acrylic acid. By decreasing vanadium content during synthesis, delamination to ITQ-6 was more effective, increasing accessibility and, consequently, the productivity of sites.
COMPETITION BETWEEN DECARBOXYLATION AND ISOMERIZATION IN THE C3H5O2(1+) ENERGY SURFACE. JUSTIFICATION OF THE EXPERIMENTAL RESULTS BY MOLECULAR ORBITAL CALCULATIONS ON THE SOLVATED IONS
Rajadell, Fernando,Planelles, Josep,Tomas, Francisco,Asensio, Gregorio,Miranda, Miguel A.,Sabater, Maria J.
, p. 221 - 226 (1994)
In contrast with recent molecular orbital calculations on the decarboxylation of O-protonated 2-oxetanone, this experimental work indicates that no decarboxylation of this cation occurs in sulphuric acid solution up to 150 deg C, but instead a clean isomerization to protonated acrylic acid takes place.Parallel theoretical work shows that the gas-phase model is too crude to account successfully for the experimental facts obtained in acidic media.However, the latter are well reproduced when the effect of the solvent is taken into account.The present findings do not necessarily invalidate the reaction mechanism currently accepted to explain the rate enhancement and change of stereochemistry accompanying the decarboxylation of 3,4-disubstituted 2-oxetanones under acid catalysis.
Facile sub-/supercritical water synthesis of nanoflake MoVTeNbO:X-mixed metal oxides without post-heat treatment and their catalytic performance
Deng, Luyao,Fan, Yaoxin,Li, Shuangming,Liu, Yongwei,Lu, Zixuan,Yan, Yunong,Yu, Sansan,Zhang, Zhe
, p. 39922 - 39930 (2020)
A fast and simple sub-/supercritical water synthesis method is presented in this work in which MoVTeNbOx-mixed metal oxides with various phase compositions and morphologies could be synthesized without post-heat treatment. It was demonstrated that the system temperature for synthesis had a significant influence on the physico-chemical properties of MoVTeNbOx. Higher temperatures were beneficial for the formation of a mixed crystalline phase containing TeVO4, Te3Mo2V2O17, Mo4O11 and TeO2, which are very different from the crystalline phases of conventional Mo-V-Te-Nb-mixed metal oxides. While at lower temperatures, Mo4O11 was replaced by Te. At high temperature, the as-prepared samples presented distinct nanoflake morphologies with an average size of 10-60 nm in width and exhibited excellent catalytic performances in the selective oxidation of propylene to acrylic acid. It is illustrated that the large specific surface area, presence of Mo4O11 and superficial Mo6+ and Te4+ ions are responsible for the high propylene conversion, while suitable acidic sites and superficial Nb5+ ions improved the selectivity to acrylic acid. This journal is
How important is the (001) plane of M1 for selective oxidation of propane to acrylic acid?
Celaya Sanfiz,Hansen,Sakthivel,Trunschke,Schloegl,Knoester,Brongersma,Looi,Hamid
, p. 35 - 43 (2008)
The role of the (001) crystallographic plane of the M1 phase of MoVTeNb mixed-oxide catalysts in selective oxidation of propane to acrylic acid was addressed by investigating a phase-pure M1 material preferentially exposing this surface. A model catalyst was prepared by complete silylation of M1, followed by breakage of the SiO2-covered needles. Using this approach, the reactivity of the M1 (001) surface was investigated by combining a microreactor study of propane oxidation with high-sensitivity low-energy ion scattering (HS-LEIS). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the shape and microstructure of the model system and verify the surface exposure of the model catalyst. The specific rate of formation of acrylic acid on the model catalyst was found to be similar to that on the phase-pure M1 reference material, indicating that the (001) plane of the M1 crystal structure did not have better catalytic properties compared with the lateral surface of M1 needles in propane oxidation.
The regional hydrolysis of ethyl acrylate to acrylic acid in the rat nasal cavity
Frederick, Clay B.,Udinsky, John R.,Finch, Lavorgie
, p. 49 - 56 (1994)
Cytotoxicity is primarily limited to the olfactory epithelium of the dorsal meatus region of the nasal cavity of rodents following inhalation exposure to acrylic monomers. To investigate the biochemical basis for this effect, three regions of the Fischer F344N rat nasal cavity were evaluated for carboxylesterase activity for the representative acrylic ester, ethyl acrylate. Prior studies have indicated that the rodent olfactory epithelium is sensitive to the cytotoxic effects of short chain organic acids. In this study, no regional difference in carboxylesterase activity was observed between sensitive and non-sensitive regions of olfactory epithelium. Respiratory epithelium (resistant to cytotoxicity) was found to have a much lower rate of carboxylesterase activity than olfactory epithelium. These results suggest that the regional distribution of cytotoxicity observed in the rat nasal cavity at high concentrations of inhaled acrylic monomers may be due in part to the amount of released organic acid following deposition. However, the observation of the same esterase activity in sensitive and nonsensitive olfactory regions suggests that nasal air flow patterns and regional deposition may also be critical factors.
Pd@Zn-MOF-74: Restricting a Guest Molecule by the Open-Metal Site in a Metal-Organic Framework for Selective Semihydrogenation
Wu, Hui Qiong,Huang, Ling,Li, Jian Qiang,Zheng, An Min,Tao, Yuan,Yang, Li Xiao,Yin, Wen Hui,Luo, Feng
, p. 12444 - 12447 (2018)
In this work, we found that the open-metal site in a metal-organic framework (MOF) can be used to enhance such selectivity. Hydrogenation of phenylacetylene over such a catalyst enables ultrahigh styrene selectivity of 92% at full conversion with a turnover frequency of 98.1 h-1. The origin of ultrahigh selectivity, as unveiled by density functional theory calculation, is due to a coordination interaction between the open Zn(II) site and the C≡C bond of phenylacetylene.
Kinetics of osmium(VIII) catalyzed oxidation of allyl alcohol by potassium bromate in aqueous acidic medium-autocatalysis in catalysis
Desai,Halligudi,Nandibewoor
, p. 583 - 589 (1999)
The kinetics of oxidation of allyl alcohol with potassium bromate in the presence of osmium(VIII) catalyst in aqueous acid medium has been studied under varying conditions. The active species of oxidant and catalyst in the reaction were understood to be Bro3- and H2OsO5, respectively. The autocatalysis exhibited by one of the products, that is, Br-, was attributed to complex formation between bromide and osmium(VIII). A composite scheme and rate law were possible. Some reaction constants involved in the mechanism have been evaluated.
