Process Intensification of n‐Butane Oxidation to Maleic Anhydride in a Millistructured Reactor

Abstract

Dedicated to Professor Rüdiger Lange on the occasion of his 65th birthdayThe oxidation of n-butane to maleic anhydride over an industrial vanadyl pyrophosphate oxide catalyst was investigated experimentally in millistructured reactors with varying slit widths to investigate the process intensification potential of this reaction. Although the smaller reactor behaved isothermally, even in the presence of high n-butane concentrations, moderate hot spots never exceeding more than 15 K above the salt bath temperature occurred in the larger catalyst channel. After exposure to high n-butane concentrations, a certain amount of catalyst deactivation was observed, which could be partly restored through reoxidation with pure oxygen. The reactor-specific maleic anhydride productivities obtained are much larger than those in conventional multitubular reactors.

Millistructured Reactor as Tool for Investigating the Kinetics of Maleic Anhydride Synthesis

“…As already shown by Hofmann for a reactor with a slit width of 1.5 mm instead of the 1.65 mm used here, the reactor behaves almost isothermally. Even at high space velocities of up to 4800 m N 3 m −3 h −1 and over 90 % conversion, the measured temperature of the catalyst bed is at maximum 5 K above the temperature of the surrounding salt bath.…”

“…These low hot spots compared to industrial reactors allow an operation at higher butane concentrations than the usual maximal 1.8 % in industry. As shown by Hofmann , a runaway of the reactor does not occur even at concentrations significantly above (up to 4.5 %) the lower explosion limit. To ensure comparability with industrial conditions, the concentration of butane was limited to 2.1 % for the present work.…”

“…The experiments were performed in a millistructured fixed‐bed reactor with a catalyst bed of 44 × 72 × 1.65 mm, that was derived from the concept described by Hofmann . As depicted in Fig.…”

“…Therefore, the aim of ongoing research is to investigate the phosphorus dynamics under well-defined conditions. The millistructured reactor used in this work, originally developed by Hofmann [10], offers optimal conditions due to its virtually isothermal behavior as it allows a separation of the influences of the hotspot from other kinetic effects.…”

Phosphorus Dosing during Catalytic n-Butane Oxidation in a μ-Reactor: A Proof of Concept

“…Experiments were conducted in a slit fixed-bed reactor (hereafter referred to as μ-reactor) originally developed by Hofmann et al 29 and further improved by Muller et al 27 as shown in Figure 1. Only a brief summary of the experimental setup is given here; the authors refer the reader to the Supporting Information (chapters S1−S3) and the original publications by Hofmann et al 29 and Muller et al 27 for a more detailed description.…”