CHEMICAL ENGINEERING TRANSACTIONS VOL. 26, 2012 A publication of The Italian Association of Chemical Engineering Online at: www.aidic.it/cet Guest Editors: Valerio Cozzani, Eddy De Rademaeker Copyright © 2012, AIDIC Servizi S.r.l., ISBN 978-88-95608-17-4; ISSN 1974-9791 Preserving Safety and Improving Yield Performances in Methanol Processes Zohreh Ravaghi-Ardebili a , Flavio Manenti* a , Nadson M. Nascimento Lima b , Lamia Zuniga Linan b , Silvia Cieri c , Marco Restelli c , Giulia Bozzano a a Politecnico di Milano, CMIC dept. “Giulio Natta”, Piazza Leonardo da Vinci 32, 20133 Milano, ITALY b University of Campinas (UNICAMP), Department of Chemical Processes, PO Box 6066, 13081-970, Campinas, São Paulo, BRAZIL c Novartis Vaccines & Diagnostics, Via Fiorentina 1, 53100 Siena, ITALY flavio.manenti@polimi.it The industrial best practice for methanol synthesis is the use a fixed-bed tubular reactor. The exothermic nature of methanol synthesis, the possibility to activate the methanation reaction (intensely exothermic) and the discrete nature of temperature acquisition throughout the reactor claim for novel technological solutions for process control and optimization. Specifically, the aim of this work is to monitor the hot-spot temperature and to manipulate it to improve the yield of methanol. 1. Introduction Even though many improvements have been made since its first industrial technology, in 1923, and a series of new production technologies are being developed (Lange, 2001; Olah et al., 2009; Basri et al., 2009; Gomez-Castro et al., 2010; Mayra and Leiviska, 2009; Sie et al., 2009), methanol is still largely produced, with very low conversions, from natural gas, specially via synthesis gas (or syngas, CO and H2 mixture). The latter is produced by means of steam reforming operations. Moreover, the methanol process is usually characterized by high potentiality, relatively high pressure, and some side reactions that must be controlled to prevent any operational risk. In this context, it is difficult to maintain the performances of methanol conversion, while the safety of the operations must be fulfilled; this further contributes to the yield in methanol less than 7 %. For example, the well-established directives are to operate the methanol synthesis reactor in the range 500-540 K (Lommerts et al., 2000; Graaf et al., 1986; Graaf et al., 1988). Lower temperatures correspond to poor catalyst activity, whereas higher temperatures activate the so-called methanation reaction: 2 4 2 3 CO H CH HO    (1) Even if the methanation reaction, which is provided by the copper coating, takes place at more than 570 K, the safety threshold of operation is estimated around 540 K. It accounts for the fact that the overall reaction process from syngas to methanol is exothermic and, therefore, the reaction environment moves towards higher temperatures. In addition, being the system kinetically controlled for the first part of the reactor and thermodynamically controlled for the remaining part, the temperature profile of the methanol reactor is characterized by a maximum so called hot-spot (Manenti et al., 2011a; Manenti et al., 2011b). Nevertheless, the temperature is measured by a multi-thermocouple, 69