Catalyst For Ring Opening Research Articles

Reactivation of Industrial Spent Hydrocracking Catalyst for Tetralin Selective Hydrogenation and Ring-Opening

Reactivation of Industrial Spent Hydrocracking Catalyst for Tetralin Selective Hydrogenation and Ring-Opening

Understanding the Role of Base Species on Reversed Cu Catalyst in Ring Opening of Furan Compounds to 1, 2-Pentanediol.

The hydrogenation of biomass-derived furan compounds provides a sustainable pathway for the production of various valuable chemicals; product selectivity among multiple reaction pathways of furan compound hydrogenation is crucially dependent on catalytic sites; however controlling reaction pathways remains challenging due to the lack of identification and understanding of active sites. In this work we reveal the role of base sites in furfural selective hydrogenation through deliberately designed and synthesized reversed catalysts, basic metal oxides and hydroxide on Cu. It is demonstrated that base species greatly enhanced the selectivity of 1, 2-pentanediol (1, 2-PeD) from furfural, presenting a nearly fourfold increase of 1, 2-PeD: methyl furan ratio over the Cu based reverse catalysts. A combination of infrared spectroscopy and DFT calculations demonstrates the strong interaction between the C-O-C bond in furan ring and the catalyst surface in preferentially parallel adsorption mode in the presence of base species on Cu, thus facilitating the activation of C-O-C bond to produce 1, 2-PeD. This work provides a strategy of designing reversed catalyst to study the effect of promoters and reveals the role of base sites in the hydrogenation of biomass-derived furan compounds to diols.

Imidazolium-based ionic liquid supported layered silicate HUS-7 as an active catalyst for ring opening of oxiranes

Imidazolium-based ionic liquid supported layered silicate HUS-7 as an active catalyst for ring opening of oxiranes

BF3/HY as a microporous solid acid catalyst for regioselective ring-opening of epoxides

A solid acid catalyst BF3/HY was synthesized and used for regioselective ring-opening of epoxides; different aldehydes could be obtained with exceptional yields and selectivity.

Robust salen-typed Ce-MOFs supported Fe(III) catalyst fabricated by metalloligand strategy for catalytic epoxides with alcohols

A salen-based Ce-MOFs contained rich uncoordinated imine (−CH=N−) groups (termed as N-Ce-salen) has been synthesized by using solution-diffusion method. Furthermore, the as-synthesized N-Ce-salen MOFs served as a “metalloligand” could coordinate with Fe(III) ions forming a MOFs supported Fe(III) ions catalyst via a coordination assisted preparation strategy (named as Fe-N@Ce-salen-CAP). The coordination between the uncoordinated imine (−CH=N−) and Fe(III) ions was characterized by 13C solid-state NMR, N 1s XPS, FT-IR and UV-Vis techniques. The developed Fe-N@Ce-salen-CAP catalyst delivers excellent performance for ring-opening of epoxides with alcohols reaction in comparison with that Ce-salen MOFs (using the same organic linker) without containing uncoordinated imine groups supported Fe(III) catalyst (named as Fe/Ce-salen-IWI) prepared by classic incipient wetness impregnation (IWI) method. Various characterization techniques, e.g. XPS, TEM, HADDF-STEM, were employed to reveal the origin of enhanced performance of Fe-N@Ce-salen-CAP catalyst for ring-opening of epoxides with alcohols. We anticipate that this coordination-assisted preparation strategy may provide a new avenue for synthesis of other highly efficient MOFs supported catalysts for other heterogeneous catalytic reactions.

Elucidating the Morphology Effect of Pt Nanocrystals on Pt/CNT-USY Catalysts for Selective Ring Opening of Decalin

Elucidating the Morphology Effect of Pt Nanocrystals on Pt/CNT-USY Catalysts for Selective Ring Opening of Decalin

Improving and stabilizing fluorinated aryl borane catalysts for epoxide ring-opening

Epoxide ring-opening is a key reaction in organic chemistry. We have previously shown that B(C6F5)3, a strongly Lewis acidic arylborane, exhibited high rates and unusual selectivities for catalyzing the ring-opening of aliphatic epoxides with alcohols. Here we compare catalysts of the form B(C6H5−XFX)3 (x = 5, 4, 3, and 0) and determine that moderately Lewis acidic arylboranes have higher regioselectivity, but slower rates in this reaction. At high temperatures, these arylboranes can also hydrolyze into inactive species. However, deactivation is suppressed in the presence of co-catalytic amounts of 1,2-propanediol, and DFT calculations suggest a role for arylborane-H2O-diol complexes. Thermal stabilization and regioselectivity enhancement by diol are both more pronounced for B(C6F5)3 than for less Lewis acidic B(C6HF4)3 and B(C6H2F3)3 catalysts. These results further demonstrate the catalytic relevance of H-bound networks of arylboranes and diols and enable their use at higher temperatures and greatly increased rates.

Catalytic selective ring opening of polyaromatics for cleaner transportation fuels

Selective ring opening (SRO) catalysts transform polycyclic molecules in low grade oil to produce cleaner burning diesel fuel. Mechanistic insight, structure-reactivity relationships, catalyst design, and future opportunities for pyrolysis oil refining from municipal solid waste are discussed.

Cross‐linked poly(N‐vinylpyrrolidone)‐titanium tetrachloride complex: A novel stable solid TiCl4 equivalent as a recyclable polymeric Lewis acid catalyst for regioselective ring‐opening alcoholysis of epoxides

AbstractCross‐linked poly(N‐vinylpyrrolidone) resin beads were prepared as macromolecular ligand precursors by suspension copolymerization of N‐vinyl‐2‐pyrrolidone and N,N′‐methylenebisacrylamide (MBA) as a crosslinking agent in water. Subsequently, the resulting polymer carrier precursor was readily combined with titanium tetrachloride to form a stable polymeric coordination complex (PNVP/TiCl4), and this novel stable TiCl4 equivalent evaluated as a heterogeneous and reusable solid Lewis acid catalyst for the regio‐and stereoselective nucleophilic ring opening of various epoxides with various alcohols to prepare β‐alkoxy alcohols in excellent yields without generating any waste. The MBA‐cross‐linked PNVP and resultant catalyst were characterized by Fourier transform infrared spectroscopy (FT–IR), field‐emission scanning electron microscope (FE–SEM), energy dispersive X‐ray (EDX), inductively coupled plasma (ICP), and thermogravimetric analysis (TGA) techniques. Moreover, the catalyst is very stable, easily separated, and reused at least five times without significant loss of activity. In terms of scope, yields, the amount of catalyst used, and reaction time, the PNVP‐TiCl4 complex catalyst is an improvement over previously reported heterogeneous catalysts for ring opening of epoxides methods. Further, the experimental outcome revealed that using the copolymer beads as carriers with a high percentage of crosslinking and the high mesh size leads had an adverse effect on the reaction rate.

A novel copper framework with amino tridentate N‐donor ligand as heterogeneous catalyst for ring opening of epoxides

A novel metal–organic framework (MOF) [Cu3L(2,6‐NDC)2]·0.5DMF (MOF‐Cu‐1) was synthesized by solvothermal reaction of copper nitrate trihydrate with 2,6‐naphthalenedicarboxylic acid (2,6‐H2NDC) and amino tridentate N‐donor containing ligand of N1‐(4‐(1H‐imidazol‐1‐yl)benzyl)‐N1‐(2‐aminoethyl)ethane‐1,2‐diamine (L). MOF‐Cu‐1 is a three‐dimensional (3D) framework with one‐dimensional (1D) channels. Because of the high stability of the framework and the existence of amino functional groups, MOF‐Cu‐1 presents excellent heterogeneous catalytic activity for ring‐opening reaction of epoxides by amines and reusability for four cycles with negligible loss of efficiency.

Influence of the Ir content and the support on the thiotolerance of the Ir/SiO2‐Al2O3 catalysts for selective ring opening of decalin

AbstractThe influence of Ir content on sulphur tolerance for the selective ring opening of decalin was investigated. Ir/SiO2‐Al2O3 catalysts (70 wt% and 80 wt% SiO2) were used. In the absence of sulphur, slight differences were observed on the yields according to the metallic content regardless of the support used. Although the results of cyclopentane hydrogenolysis showed that the metallic function acquires importance as the metal content increases, for these metal percentages the acid function limits the rate of decalin opening reaction. Products distribution are strongly modified using decalin with S content compared to pure decalin. The formation of dehydrogenated products is virtually null due to S adsorbed on the metal sites. The support has low influence on the thiotolerance. The results, related to the amount of S per Ir surface atom, showed that for a moderate S content (S/Irsurf ∼ 0.30), 1.5 Ir/Sy appears to be less poisoned than 1Ir/Sy and 2Ir/Sy.

Transition metal sulfides on zeolite catalysts for selective ring opening

Bifunctional catalysis combining acidic catalysts and sulfide active phases is usually related to hydrocracking catalysts which balances the hydrogenation function of a NiMo (NiW) alumina supported sulfide catalysts and the acidic function of a zeolite. The discovery of sulfur-resistant catalysts for selective ring opening (SRO) is an important challenge for refiners, considering the future legislation on cetane index of diesel fuels. In the present work, we studied the properties of various transition metal sulfides (TMS) supported on Y zeolite in gas-phase decalin hydroconversion at high hydrogen pressure (5 MPa) in the presence of 0.8 % H2S concentration. This screening shows high activities for noble metal based sulfides with a mechanism which proceeds by skeletal isomerization induced by the zeolite. Catalytic activity was improved by the use of ternary sulfides such as Ni1-xRuxS2 or NiRh2S4 on Y zeolites. High decalin conversion levels can be reached below 250 °C with more of 20 % of ring opening products and thanks to the use of comprehensive GC, a detailed mechanism of the SRO of decalin is given.

Greener and regioselective ring opening of epoxides with TMSCN using potassium salts of magnetic carbon nitride

Potassium salts of magnetic graphitic carbon nitride (Fe3O4@g-C3N4-K) synthesized and proved to be a green and recyclable catalyst for rapid and regioselective ring opening of epoxides with TMSCN, yielding the β-hydroxynitrile ring-opened products under mild reaction conditions. It is manageable to large-scale preparation with simple instruments and gives the desired compounds in short reaction times with good-to-excellent yields (73–95%) under solvent-free conditions. Magnetic separation protocol has used to achieve a simple separation and reuse of catalysts from unpurified reaction mixtures using external magnets without loss of catalytic operation after five cycles.

Selective Ring Opening of Ethylbenzene on Bifunctional Catalyst Pt–Ir over Hierarchical USY Zeolite

A bifunctional catalyst for selective ring opening (SRO) has been designed using a hierarchical zeolite as support. This material was prepared introducing additional mesoporosity in the microporous structure of a USY zeolite, by surfactant-templating post-synthetic mesostructuring process. Monometallic and bimetallic Pt(x)−Ir(y) catalysts with different metal loadings and Pt/Ir mole ratio have been prepared. In addition, to optimise the acid-metal balance, the acidity of the support has been modulated via ion-exchange process with Na+. The catalytic behaviour of the prepared materials has been evaluated with ethylbenzene hydrogenation and SRO simultaneous reaction in a continuous-flow fixed-bed reactor, at 275°C and 3 MPa. Pt(2)−Ir(1) resulted the most promising metallic combination. The high hydrogenolytic activity of Ir, along with the high hydrogenation activity and cracking limitation of Pt attained a high paraffins production. This behaviour was improved modulating the acidity of the support. Thus, Pt(2)−Ir(1)/Na−FAU−CTAB catalyst maximized the yield to paraffins which improve the cetane number of fuels.

MIL-101(Fe) as an active heterogeneous solid acid catalyst for the regioselective ring opening of epoxides by indoles

Ring opening of an epoxide by a nucleophile is considered as one of the viable strategies to prepare biologically active molecules using homogeneous or heterogeneous Lewis acid catalysts. Very often, the ring opening of epoxide was performed with oxygen, sulfur and nitrogen based nucleophiles. Recently, metal organic frameworks (MOFs) were identified as one of the promising solid heterogeneous catalysts for ring opening of epoxide with oxygen and nitrogen based nucleophiles, but however, use of carbon nucleophile like indole is limited. Hence, the present work reports the catalytic performance of MIL-101(Fe) as a highly active regioselective heterogeneous solid Lewis acid catalyst in promoting the ring opening of styrene oxide by indole. Among the various catalysts employed for this reaction, MIL-101(Fe) exhibited the highest catalytic activity. A series of control experiments indicated the pivotal role played by Lewis acids within the frameworks of MIL-101(Fe) and further, the catalytic reaction was found to be heterogeneous in nature as evidenced by leaching test. Further, MIL-101(Fe) was reused four cycles with no decay in its activity. Also, MIL-101(Fe) exhibited wide substrate scope in providing series of heterocyclic compounds in moderate to higher yields. A suitable mechanism was also proposed considering the present results and the knowledge from the literature.

A Thiophene-2-carboxamide-Functionalized Zr(IV) Organic Framework as a Prolific and Recyclable Heterogeneous Catalyst for Regioselective Ring Opening of Epoxides.

A new thiophene-2-carboxamide-functionalized Zr-UiO-66 MOF (1) was synthesized by employing a traditional solvothermal procedure. Compound 1 displayed high thermal (up to 340 °C under an Ar atmosphere) and chemical stability (in water, 1 M HCl, and acetic acid). A nitrogen physisorption measurement with the activated form of 1 (denoted 1') exhibited a BET surface area (781 m2/g) despite attachment of a bulky side chain with the linker molecule. Compound 1' was able to heterogeneously catalyze the ring-opening reaction of epoxides with amines. Catalyst 1' exhibited significant yields as well as wide substrate scope in the ring opening of epoxides by means of amines. It also displayed better catalytic performance in comparison to known MOF catalysts such as Cu3(BTC)2, Fe(BTC)(BTC: 1, 3, 5-benzenetricarboxylate), and Zr-UiO-66. Control experiments were performed with free linker, Zr(IV) salt and without catalyst 1', confirming the exclusive role of 1' in the catalytic reaction. The reusability characteristics of catalyst 1' was established for up to five consecutive catalytic cycles. The synthesis and characterization of the linker molecule, material 1, and 1' and mechanism of the catalysis reaction were studied elaborately.

Active Copper Catalyzed Regioselective Ring Opening of Epoxides by Heterocyclic Amines: An Efficient Protocol for Synthesis of β-Amino Alcohols

The regioselective epoxide ring opening at less substituted carbon atom of epoxide were reported by nucleophiles like heterocyclic amines which gives well known 1,2-difunctionalized amino alcohols. These are present in many synthetic as well as natural products. The ring opening of epoxide is achieved by cleavage with amines in presence of copper(0) as a catalyst. It is observed that the lithium napthalenide reduction of copper(I) produces a highly reactive form of copper(0) that acts as a catalyst for ring opening of epoxides with an amine.

Pt–Ir/Al2O3 catalysts for the ring opening of naphthenes. Performance as a function of time

The catalytic performance of a Pt–Ir/Al2O3 catalyst for the selective ring opening of decalin was studied as a function of time. Fresh and used catalysts were evaluated with the reaction tests of cyclohexane dehydrogenation and cyclopentane hydrogenolysis to assess the metal function properties. The transformation of decalin was used as a test reaction for the ring opening of naphthenes. For this test the yield to ring contraction products passed through a maximum at intermediate values of conversion while yields to dehydrogenation, ring opening, and cracking products increased with conversion. Coke deposition also increased with reaction time but its distribution on the metal and acid sites did not change. Coke was more toxic for hydrogenolysis than for de/hydrogenation and therefore the products ratio of (ring opening)/(dehydrogenation) decreased at end of the reaction. Higher yields to dehydrogenated products produced a higher coke deposition while high activity in both hydrogenolysis and dehydrogenation favored the ring opening reaction.

Mechanistic Approaches toward Rational Design of a Heterogeneous Catalyst for Ring-Opening and Deoxygenation of Biomass-Derived Cyclic Compounds

Technologies for the processing of lignocellulosic biomass into fuels and chemicals are generally focused on selective chemical transformation of the three different types of constituents: cellulose, hemicellulose and lignin. In this regard, heterogeneous catalytic reactions are employed to defunctionalize and upgrade the platform molecules obtained selectively from these constituents. Herein, a selection of studies are discussed which are adapted to deoxygenate and valorize the biomass-derived platform molecules with a specific focus on understanding the reaction mechanisms and rational design of a heterogeneous catalyst. The selection of the deoxygenation process constituted a combination of two or three reactions. For example, ring-opening reactions of the cyclic compounds are studied with decarboxylation, dehydration, hydrogenation and/or Diels–Alder reaction carried out on metal, acid and/or oxide catalysts. The platform molecules studied here include an array of saturated lactones, 2-pyrones, cyclic...

In-situ evaluation for upgrading of biomass over noble metal catalysts by isotopic tracing and NMR monitoring

One of the key challenges in studying the upgrading processes for the conversion of biomass is developing an understanding of the underlying conversion mechanism at the atomic scale. This study proposed an innovative high pressure in situ NMR monitoring approach for an isotopic traced upgrading process, which demonstrated a powerful capability to identify key products and provide insights into the reaction structure. The investigations for ring opening of two basic model compounds – methylcyclopentane (MCP) and cyclohexane (CH) on Ir, Pt, Ru and Pd/γ-Al2O3 at 55 and 110 °C have been accomplished. For the study performed at 110 °C on Ir, Pt and Ru catalysts, the trend of H/D exchange rates were clearly dependent on the position on the ring with the highest exchange rate for the unhindered (or open side) and the lowest rate with the methyl group. However, Pd could perform almost equally efficient H/D exchanges for all sides, which may indicate that the “turnover” reactions could also occur on Pd. For both MCP and CH, Ru performed the most efficient H/D exchanges (C–H bond activation), and ring opened products were only observed with the Ru catalyst at 110 °C suggesting it is the most promising ring opening catalyst.