Solid Superbase Catalyst Research Articles

Synthesis of tert-amylbenzene for side-chain alkylation of cumene catalyzed by a solid superbase

Abstract The side-chain alkylation of cumene and ethylene over a solid superbase catalyst K/KOH/γ-Al2O3 is investigated. The effects of the reaction temperature, pressure, and time on the conversion of cumene and selectivity of tert-amylbenzene (TAB) are discussed. The experimental results show that the conversion of cumene to tert-pentylbenzene increases with the increase in reaction temperature and ethylene pressure. The catalytic reaction has certain operational flexibility in terms of the reaction temperature, pressure, and time. In addition, the catalytic reaction can achieve directional conversion. The optimum operating conditions are obtained using a single factor test. The conversion of cumene is 99.8% and the selectivity toward TAB is 97.9% under catalyst concentration of 4 wt%, reaction temperature of 55°C, reaction pressure of 0.45 MPa, and reaction time of 30 min. The deactivation of catalyst is mainly caused by oxygen and water in the raw material.

Directional Catalytic Hydroconversion of Oxybis (methylene)dibenzene and an Extract from Piliqing Subbituminous Coal over a Magnetic Difunctional Solid Superbase

AbstractAn active and novel magnetic difunctional solid superbase catalyst Ni‐Mg2Si/attapulgite powder (AP) was prepared by thermally decomposing nickel tetracarbonyl onto the as‐synthesized Mg2Si/AP followed by impregnating Mg2Si onto AP in CCl4 and characterized by multiple analyses. It was also successfully used in the catalytic hydroconversion (CHC) of coal‐related model compound oxybis (methylene) dibenzene (OBMDB) and an extract (E) from Piliqing subbituminous coal (PSBC) in n‐hexane. As a result, OBMDB was completely converted to methylcyclohexane by the CHC under 3 MPa of initial hydrogen pressure at 240 °C for 2 h. Ni‐Mg2Si/AP can activate H2 to biatomic active hydrogen (H…H) and split H2 to immobile H+ attached on the Ni‐Mg2Si/AP surface and relatively mobile H−. Then the bridged linkage (BL) in OBMDB can be cleaved by H− attack on a α‐carbon atom in OBMDB, producing toluene and benzyloxy anion, which abstracts H+ from the Ni‐Mg2Si/AP surface to afford phenylmethanol (PM). The α‐carbon in PM is attacked by H‐ to generate toluene and HO−. H…H transfers to benzene ring in toluene yields methylcyclohexane. The soluble portion (SP) from the CHC (SPE‐CHC) and non‐CHC (NCHC) (SPE‐NCHC) of E were analyzed with a gas chromatograph/mass spectrometer and Fourier transform infrared spectrometer. Non‐substituted cycloalkanes (NSCAs) are predominant in the SPE‐CHC, accounting for 66.9 % of the total group components, and interestingly 65.3 % of NSCAs is cyclohexane, while non‐substituted arenes are the most abundant in the SPE‐NCHC. The results indicate that the CHC is beneficial to the fracture of COCBB and hydrogenation of ARs to produce more NSCAs.

A novel strategy for constructing mesoporous solid superbase catalysts: bimetallic Al–La oxides supported on SBA-15 modified with KF

Bimetallic Al–La oxides were conjointly precoated on SBA-15 prior to the introduction of potassium fluoride to achieve solid superbases at low temperature by a modified wetness impregnation method.

Novelty of Claisen–Schmidt condensation of biomass-derived furfural with acetophenone over solid super base catalyst

Download options Please wait... Supplementary files Supplementary information PDF (364K) Article information DOI https://doi.org/10.1039/C4RA09194A Article type Paper Submitted 25 Aug 2014 Accepted 10 Nov 2014 First published 11 Nov 2014 Download Citation RSC Adv., 2014,4, 63772-63778 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Novelty of Claisen–Schmidt condensation of biomass-derived furfural with acetophenone over solid super base catalyst G. D. Yadav and A. R. Yadav, RSC Adv., 2014, 4, 63772 DOI: 10.1039/C4RA09194A To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Ganapati D. Yadav Akhilesh R. Yadav

Research Progress on Solid Superbase Catalysts in the Last Decade

Research Progress on Solid Superbase Catalysts in the Last Decade

Novel and versatile solid superbases derived from magnesium–zirconium composite oxide and their catalytic applications

Versatile solid superbases were derived from magnesium–zirconium composite oxide and KOH through thermal treatment in a N2 flow. The magnesium–zirconium composite oxide was prepared by a modified co-precipitation technique with reflux-digestion in basic solution and then mixed with KOH through grinding. The as-prepared solid superbases were characterized by low-temperature N2 physisorption, powder X-ray diffraction, and Fourier transformation infrared spectrophotometry. The superbasic sites were characterized by the use of Hammett indicators and CO2 temperature-programmed desorption methods. We found that there are ample superbasic sites (0.590 mmol g−1) on the surface with strength in the 26.5 ≤ H− < 33.0 range. The as-prepared solid superbase catalyst was found to show excellent catalytic activity towards Knoevenagel condensation, Michael addition and transesterification reactions. The findings open up a new route for the synthesis of new functional superbases using composite oxides prepared by reflux-digestion in basic solution as supports.

One-pot synthesis of potassium-loaded MgAl oxide as solid superbase catalyst for Knoevenagel condensation

We report a new strategy for one-pot synthesis of potassium-loaded MgAl oxides using KOH to adjust the pH value of the reaction system. The as-prepared solid superbases were studied by N2 physisorption method, energy-dispersive X-ray spectroscopy, powder X-ray diffraction, and Fourier transform infrared. The superbasic sites were characterized by the use of Hammett indicators and CO2 temperature-programmed desorption. We found that with a base strength (H–) above 26.5, the potassium-loaded MgAl oxides showed high catalytic activity for Knoevenagel condensation at room temperature. Furthermore, the higher the superbasicity and/or the more the amount of superbasic sites, the better is the catalytic activity. The findings open up a new route for the synthesis of new functional superbases using composite oxides as supports.

A mini-review on solid superbase catalysts developed in the past two decades

In this mini-review, we focus on the research activities on solid superbase catalysts that have been conducted in the past two decades. We summarize the type and preparation of superbases, the mechanism for the generation of basic sites, and the applications of superbases in catalysis. It is pointed out that several kinds of superbases are reported so far with the majority of solid superbases generated using a single metal oxide as support. However, the superbases are extremely sensitive to water and CO2, and rigorous conditions are required for their preparation and utilization. As a consequence, the development and application of solid superbases is limited. Despite the understanding of formation mechanism of superbasic sites being essential for the design of solid superbases, reports on this aspect are scant. It is envisaged that composite metal oxides and porous materials should be developed as support materials to generate novel solid superbases, and our recent research results open up a new route for the design and synthesis of composite oxide superbase materials. Efforts should be devoted to study the generation of superbase sites by adopting advanced techniques for characterization and new methods for theoretical investigation. Moreover, it is predicted that solid superbases will find new applications in catalysis, especially in reactions that require high temperatures for desorption of acidic substances from surfaces of superbases.

Transesterification of Cotton-Seed Oil by Heterogeneous Solid Super Base KF/MgO Catalyst

An environmentally benign process was developed for the production of biodiesel from cotton-seed oil using KF loaded with MgO as a heterogeneous solid super base catalyst. The 20 wt% KF/MgO, after desiccated at 120 oC for 4 h, was found to be the optimum catalyst. Hammett indicator method, XRD, SEM and IR were employed for the catalyst characterization. The results showed the activity of the catalysts was correlated with their basicity. The influence of various reaction variables on the conversion, such as the molar ratio of methanol to cotton-seed oil, the catalyst amount, the reaction time and temperature were also discussed. When the transesterification reaction was carried out at reflux of methanol (65 oC), with a molar ratio of methanol to cotton-seed oil 12 : 1, a reaction time 2.5 h and a catalyst amount 2.5 wt%, the highest conversion of cotton-seed oil reached 99.14%.

Synthesis of cross-linked polyethylene oxide-acetal macrocycles for solid superbase catalysts

A novel long-chain divinyl ether of tris(diethyleneglycol)-bisacetal, has been synthesized by electrophilic addition of one molecule of diethylene glycol to two molecules of divinyl ether of diethylene glycol (DVDEG) in the presence of CF3COOH in quantitative yield. The monomer was cationically polymerized (BF3·OEt2, or complex LiBF4·MeO(CH2)2OMe) and copolymerized with DVDEG to deliver solid polymers the yields being 80–100%. The polymers represent the cross-linked polyether-polyacetal structures comprising macrocycles. The polymers were treated with 3% solution of KOH or CsOH in methanol to afford solid superbase complexes of KOH (CsOH) with cross-linked polyether-polyacetal macrocyclic networks. Preliminary tests have shown the complexes to be active catalysts for ethynylation of acetones and prototropic isomerization of methyl propargyl ethers to allenyl methyl ethers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

APLIKASI REAKSI KATALISIS HETEROGEN UNTUK PEMBUATAN VANILI SINTETIK (3-HIDROKSI-2-METOKSIBENZALDEHIDA) DARI EUGENOL (4-ALLIL-2-METOKSIFENOL) MINYAK CENGKEH

An Application of heterogenous catalysis reaction for synthesis of synthetic vanillin (3-hydroxy-2- methoxybenzaldehyde) from eugenol (4-allyl-2-methoxyphenol) of clove oil. It has been already known, that heterogeneous catalysts have more advantages compared to homogeneous catalysts. This research tried to utilize heterogeneous catalysts for an alternative reaction on synthesis of vanillin from eugenol of clove stem oil. This synthesis needs two steps reactions, isomerization reaction of eugenol to produce isoeugenol and oxidation reaction of isoeugenol to produce vanillin. Two types catalysts were used: (1) solid superbase, which was used on eugenol isomerization, and (2) phase transfer catalyst [18]-crown ether-6, which was used on oxidation of isoeugenol. Solid superbase catalyst was prepared using γ- and η-alumina, treated with sodium hydroxide and sodium metal. Alumina was extracted from kaolin from Belitung island by acid process, and the yield of aluminas were 9.0% γ-Al2O3 and 10.28% η-Al2O3. Heterogeneous catalysis study on eugenol isomerization showed that the reaction could proceed at low temperature. The eugenol isomerization reaction conditions were : temperature 10oC, reaction time 9 hours, clove stem oil 25 mmol, and solid catalyst superbase γ-Al2O3/NaOH/Na 2 g. The result of products conversion were 64.42% transisoeugenol and 6.11% cis-isoeugenol. This study included the comparison activities study of three solid superbase catalysts : γ-Al2O3/NaOH/Na, η-Al2O3/NaOH/Na, and γ-Al2O3 (E.Merck)/NaOH/Na, which showed that γ-Al2O3/NaOH/Na had better activity than those two latter solid superbase catalysts. Study on isoeugenol oxidation reaction using KMnO4 as an oxidazing agent and phase transfer catalyst [18]-crown ether-6, gave the indication that vanillin was produced mixed with other compounds. The yield of vanillin in acid medium (pH 2) was 0.021%, in neutral medium (pH 7) was 0.028% and in basic medium (pH 9) was 0.015%. Keywords: vanillin, heterogeneous catalysis, superbase catalyst; phase transfer catalyst

A Novel La&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-ZnO/ZrO&lt;sub&gt;2&lt;/sub&gt; Solid Superbase and its Catalytic Performance for Transesterification of Soybean Oil to Biodiesel

A novel solid superbase catalyst of La2O3-ZnO/ZrO2 was prepared, and its H– value (Hammett function) of surface basic strength reaches 26.5. The catalytic activity of La2O3-ZnO/ZrO2 was evaluated for the transesterification of soybean oil (SBO) with methanol to biodiesel in a fixed bed reactor under atmospheric pressure. The results show that the chemical composition of the La2O3-ZnO/ZrO2 catalyst influences both its H– value and catalytic performance, the appropriate content of ZrO2 is 60 wt.% and the La2O3/ZnO molar ratio is 4~5/1. La2O3-ZnO/ZrO2 is an effective catalyst for the transesterification of SBO, and the SBO conversion reaches 71.3% at 70°C for 12h.

A novel solid superbase of Eu2O3/Al2O3 and its catalytic performance for the transesterification of soybean oil to biodiesel

A novel solid superbase catalyst of Eu 2 O 3 /Al 2 O 3 was prepared and its basic strength reached 26.5 measured by indicators according to Hammett scale. The catalytic activity of Eu 2 O 3 /Al 2 O 3 was evaluated for the transesterification of soybean oil with methanol to biodiesel in the fixed bed reactor and under atmospheric pressure. The results show that Eu 2 O 3 /Al 2 O 3 is an excellent catalyst for the transesterification of soybean oil, and the conversion of soybean oil can reach 63.2% at 70 °C for 8 h.