Evaluation of Catalysts for the Metathesis of Ethene and 2-Butene to Propene

Matthias Felischak,Christof Hamel,Leo Alvarado Perea,Tanya Wolff,Andreas Seidel-Morgenstern

doi:10.3390/catal12020188

Abstract

Different metathesis catalysts were evaluated regarding their activity for propene production from ethene and trans-butene feedstocks. Nickel, molybdenum, rhenium and tungsten, along with bimetallic nickel-rhenium systems were applied with commercial supports and self-synthesized MCM-41. For the latter support the Si/Al ratio was adjusted as an additional optimization parameter (Si/Al = 60). Attractive activities were observed using Re and NiRe based catalysts at moderate temperatures of 200–250 °C. In contrast, the tungsten-based catalysts were only active above 450 °C. Three catalysts, namely Re/AlMCM-41(60), NiRe/mix (1:1) and W/SiO2 offered propene selectivity’s exceeding 40% at attractive conversion rates. These catalysts were characterized by BET, powder XRD, NH3-TPD and TPR-TPO-TPR cycles. At specific reaction temperatures, reaction-regeneration cycles were performed, which revealed that for the Re and W catalysts the initial reactant conversions and propene selectivity can be recovered. In contrast, for the NiRe catalyst, a continuous, gradual and irreversible decrease of activity was observed. Even though the tungsten catalyst was operated at the highest temperature, no irreversible decrease in conversion and propene selectivity occurred. Therefore, this catalyst has potential as a promising candidate for the synthesis of propene.

Highlights

In 2005, Chauvin, Grubbs and Schrock were awarded with the Nobel Prize for their research regarding the metathesis for organic synthesis [1,2,3]
The three most promising candidates are selected characterized in detail (Section 2.2) and afterwards submitted to a reaction-regeneration cycle (Section 2.3), where the resulting conversions and selectivity’s are analyzed and discussed
The (Al)MCM-41 based catalysts were synthesized by the template ion exchange (TIE) method proposed by Alvarado-Perea et al [26] via tetrabutylammonium silicate (as a mixture of tetrabutylammonium hydroxide and fumed silica (Sigma–Aldrich, Taufkirchen, Germany) and cetyltrimethylammonium bromide (Merck, Darmstadt, Germany) in deionized water

Summary

Introduction

In 2005, Chauvin, Grubbs and Schrock were awarded with the Nobel Prize for their research regarding the metathesis for organic synthesis [1,2,3]. Before Herisson and Chauvin have developed the generally accepted underlying catalytic cycle of the metathesis [4]. To optimize the production of desired components the catalysts were functionalized with organic groups [7]. A promising field is pharmaceutical production [8], where Grubbs catalysts of the second generation were utilized to produce drugs and specialty chemicals [9,10]. Schrock [11,12] achieved more stable functional groups for molybdenum and tungsten imido alkylidene complexes for specialty applications

Objectives

Methods

Results

Conclusion