Chemical Engineering and Processing 48 (2009) 329332

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Chemical Engineering and Processing:Process Intensication

journa l homepage: www.e lsev ier .co

An indu

Simon Be HaEvonik Degussa Germa

a r t i c l

Article history:Received 16 MReceived in reAccepted 19 AAvailable onlin

Keywords:Process intensMicro processMicroreactionCatalytic wallPartial oxidatiPhthalic anhydXyleneEconomic eval

esearntensessedction

exaecogn. It isss coappl

of approdu

1. Introduction

Global competition represents a major challenge to which notonly the chtion with thas the comtoday and itives and mto increaseand employUnions exteegy. In thethe Europerespect to troof underMaterials aprocess intedue primarintensicatthe chemicacorrespond

Over thecess intensi

CorresponStrae 1, D-45

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[59]. Process intensication stands for an integrated approach forprocess and product innovation in chemical research and devel-opment, and chemical engineering in order to sustain protability

0255-2701/$ doi:10.1016/j.cemical industry has to respond quickly. In connec-is frequently quoted platitude the role of innovationpetitive advantage for the European economic arean the future is often put forward [1]. Numerous initia-easures are being carried out on the European levelknowledge and innovation and attract investmentsment opportunities in accordance with the Europeanrnal competitiveness agendabased on the Lisbon Strat-recently launched Seventh Framework Programme ofan Commission such research-related initiatives withhe chemical industry are bundled together under onethe thematic priority Nanosciences, Nanotechnologies,nd new Production Technologies; here the theme ofnsication is also addressed [2]. This new interest is

ily to the fact that the conceptual idea behind procession is currently re-emerging in academia as well as inl, pharmaceutical and consumer goods sectors and theing supply industry [3,4].last decades a number of different denitions of pro-

cation have been used and published, see for example

ding author. Present address: Evonik Oxeno GmbH, Paul-Baumann-772 Marl, Germany.ress: robert.franke@evonik.com (R. Franke).

even in the presence of increasing uncertainties.

2. Innovation opportunities within the chemical industry

The chemical industry delivers goods and services tomany lead-ing industrial sectors on a global basis including a signicant extentto the chemical industry itself [10]. In response to the worldwidechanges in market demands the competitive position of the chem-ical companies relies more than ever on the ability to innovate[1012]. As a consequence innovation is increasingly becoming ametric by which corporate performance is being measured.

Properties of newly developed materials and componentsemerging from chemical companies enable other industries todevelop new products and applications in turn. The dilemma isthat, at rst sight, pureprocess innovations are oftennot interestingfrom a customers point of view. However, the efciency of produc-tion technologies andprocesses is crucial as itwill ultimately denethe competitive positioning of the chemical product. In this contextthe three generic issues chemical synthesis, apparatus technologyand plant environment will determine the strategic position ofthe producer of chemicals. Since innovation implies the economicimplementation andutilizationof new ideas in thebroader context,innovationmay also concern the structure of an organization,man-agement processes or business models. What matters is the degree

see front matter 2008 Published by Elsevier B.V.ep.2008.04.012strial view of process intensication

cht, Robert Franke , Andreas Geielmann, HenrikGmbH, Creavis Technologies & Innovation, Rodenbacher Chaussee 4, D-63457 Hanau,

e i n f o

ay 2007vised form 17 April 2008pril 2008e 26 April 2008

icationtechnologyengineeringreactoron processesride

uation

a b s t r a c t

An integrated approach in chemical rre-emerging under the label process iprocess intensication, as already exprecological efciency of chemical produhas been generally low and only a fewmicro process technology, which is rin the chemical and process industryreactions enabling almost perfect proceimprovements with regard to specicreactions is given. The incorporationwithin conventional partial oxidationm/locate /cep

hnny

ch and development, and chemical engineering is currentlyication in academia as well as in industry. The promise ofin the late 1970s, is to signicantly increase the economic androutes. However, the rate of adoption in the chemical industrymples have been reported since then. This paper addressesized as one important approach for process intensicationparticularly well suited for fast and extremely exothermic

ntrol. This feature couldpave theway for considerable processications. A brief illustration of the advantages for gas-phasepropriately designed microstructured catalytic wall reactorsction plants is presented.

2008 Published by Elsevier B.V.

330 S. Becht et al. / Chemical Engineering and Processing 48 (2009) 329332

to which the relevant organizational units such as marketing andsales, chemical research and development, process technology andengineering can be aligned to make the innovation a success.

Considering the enabling role of technology from a theoreticalpoint of view one has to differentiate between incremental anddisruptive innovations that eventually overturn the existing domi-nant technology [13,14]. Especially in industries with a demand forhighly reliable production methods it might be entirely rational toignoredisruptive innovations, since theycompare ratherbadlywithexisting technologies in that they have not been tried and proved inindustrial practice. The technical risks and uncertainties involvedtherefore often overrule the performance promise. For various rea-sons this is particularly true of the process industry and might be areason why the rate of adoption of process intensication in thechemical industry has been low and only a few examples havebeen reported since its pioneer days. An overview can be foundfor example

With reincrease prduction ofaccomplishbased asserobust econand positivis illustrateexpenditurefying techncost for theto the invehorizon isferential carate of 10%an overallinterest ratequals 6.14)capacity) theconomic nple shows tvalue of D 0capital valuing to the atypically retechnologietions.

3. Case stu

Microreasifying gas-of both heaport distan

reactions like partial oxidations [16]. For these kinds of processesthe capability of explosion suppression in microstructures is athird interesting aspect [17]. These three key effects allow a newlevel of process control: temperatures and concentrations can betightly controlled in any part of the reactor. One preferred wayof implementing microreaction technology is in the form of amicrostructured catalyticwall reactor, characterized by at least onelateral reaction volume dimension in the sub millimetre range anda solid catalyst attached to the reactor wall.

From the point of view of the chemical process industry, pro-cess control is not a value in itself but has to be transferred tocompetitive advantage. Such an advantage can be achieved bysavings in either processing or investment costs or by a reducedenvironmental impact. Savings in processing costs can be realizedby improved selectivity, extension of catalyst life time or volumereduction of recycle streams associated with higher conversions,

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nhydrin Ref. [15].gard to process intensication the goal is clearly tooductivity as dened by the relationship between pro-an output and all of the resource inputs used ining the assigned task. This includes the capital value-ssment already at the development stage. Only if aomic advantage can be derived will implementation

e perception in the industry take place. This challenged by the following example. The overall developments for setting the technological stageof aprocess intensi-

ology amounts to D 10M. Assuming that the investmentimplementation of the new technology correspondsstment in an established technology and the time10 years the annual advantage, i.e. the positive dif-sh ow as annual equivalent, at a constant interesthas to amount to D 1.63M in order to bring out

net present value of D 0. (the discount factor at ane of 10% and an underlying time period of 10 years. If the production output is for example 10kta (annualis means that the new technology has to provide anet advantage of D 163 per ton. This simple exam-hat even for a rather poor project with a net presentthe target is pretty ambitious. In net present value or

e-based economic evaluations the interest rate accord-ttributed capital cost for a non-proven technology isquired to be signicantly higher than for establisheds or the introduction of incremental process innova-

dy: catalytic wall reactor

ction technologyoffers a signicant potential for inten-phase processes. This is based on the intensicationt and mass transport processes by minimizing trans-ces and holds especially true for fast and exothermic

benetregardAlthouprocesmass eat leasmay ocontroall newadvantdue toteristicsafety.

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Fig. 1. Reaction scheme of the phthalic aich result from the discussed control advantage. Withvestment reduction the situation is less straightforward.duction of mass transport limitations and intensiedditionswill boost space timeyields, the lowvolumeandncyof amicrostructured reactor (MSR)will compensatert of this effect [16]. Signicant investment reductionse realized if the technologys potential for improvedemical conversion translates successfully into an over-

cess design, e.g. with fewer separation units. Such costusually go along with a reduced environmental impacter raw material or energy efciency with the charac-nching ability of microstructures bringing additional

crostructured catalytic wall reactors have the potentialering technology with a signicant efciency increaseic for process intensication. Together with variousacademia, Uhde and Evonik Degussa have taken ther implementation in the BMBF (German Ministry ofnd Research) funded DEMiS project. It was success-strated that micro process technology does work in a

-like environment [18] and sustainable concepts haveished.nology potential will be illustrated for the selectedthe phthalic anhydride (PA) synthesis from o-xylene.portant chemical commodity produced in a quantitymillionmetric tonsper annumwithamajor applicationediate for plasticizers. The partial oxidation of o-xyleneothermic with the formation of carbon oxides as thereactions according to the simplied scheme displayed

e three characteristic elements of the process [19] thatactive for implementing a microstructured reactor:

inct exothermic nature the effective heat generation isnge of 1500kJ/mol of xylene leads to signicant limi-

ide process.

S. Becht et al. / Chemical Engineering and Processing 48 (2009) 329332 331

tations in heat removal and pronounced temperature gradientsthroughout the reactor.

(2) The process selectivity of roughly 80% leaves room for improve-mentwhich considering amanufacturing cost contribution ofxylene feedstock ofwell above 70% results in a huge economicimpact.

(3) The xylene/air ratio denes process efciency and is limitedby safety issues due to explosion hazards. Although modernprocesses already operate beyondammability limitswith typ-ical xylene loadings of up to 100g/m3 (STP) this range may bewell extendedusingmicrostructured reactorswitheven furtherimproved safety standards.

Another aspect of this case suggests the implementation of amicrostructured reactor in the form of a booster concept asexplained in Ref. [20]. This is based on a simplied kineticmodel forphthalic anhydride according to Ref. [21], which states a pseudo-rst-order type. Accordingly, the high xylene conversion (close to100%) results in a locally inhomogeneous heat release with most ofthe heat produced in the very rst stage of the reactor, an effectwhich is further amplied by reaction rate acceleration due toinsufcient cooling. Thus, the heat transfer demand varies signif-icantly with conversion, respectively reactor length. The boosterconcept approach combines the excellent heat removal capabilityof a MSR installed upstream to deal with the major part of xyleneconversion and the high volume capacity of a downstream con-ventional multitubular reactor (MTR) for achieving full conversion.This is illustrated in Fig. 2, which shows that 63% of the total heatis released in the MSR with an effective volume of only 20% of thetotal reacto

This con

(a) Increasiyield ancentratisimilar tall yieldefcient

Fig. 2. Develoume (real reacand isothermabetween a mibooster reactoMTR.

(b) Using the relocation of conversion from the MTR to the MSR toimprove process control and safety in the sense as discussedabove.

(c) Relocatito explostream Mactive cain an oveadditionis explai

These scenAlthough thwhole proceconomic pBase is a cocess as giveare made:

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ng the xylene inlet concentration fed to the MSR tooutput xylene concentration similar to the inlet con-

on of the present MTR, i.e. this latter reactor performso the conventional setup resulting in an increased over-due to the additional capacity from the MSR operatingly at the intensied conditions.

pment of conversion and heat release over effective reactor vol-tor volume multiplied by its efciency) based on rst-order kineticsl behaviour. Distribution of converted feedstock and released heatcrostructured reactor (MSR) and a multitubular reactor (MTR) in ar concept, assuming an MSR with 20% of the effective volume of the

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To btobeadprocesFirst, acient amicrostion. Texistincoatingeven cang conversion to the MSR and then taking measuresit again the full heat removal potential of the down-TR by intensication of process conditions (e.g. moretalyst, higher pressure or temperature), which resultsrall capacity increase signicantly higher than only theal capacity of the newly installed MSR. This possibilityned in detail in Ref. [20].

arios may be applied apart or in any combination.e design of choice will depend on the details of theess including the work-up section, an estimate of theotential can be gained by some simple calculations.st distribution for the standard xed bed xylene pro-n in Ref. [22]. Furthermore, the following assumptions

r kinetics over the whole range of conversion and con-s.

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stment costs except for reactors aredependent onprod-ith a scale exponent of 0.65.

0% higher cost per capacity compared to MTR, which isive and contains a potential for optimization. Its nomi-ity, respectively effective catalyst volume, is 20% of theMTR.ts beyond depreciations are proportional to capitalt.sts reect both gains by heat generation and losses bydrop. The relative energy costs are to be seen as quali-umptions.ies are inuenced by conversion, amount of heat to beand reactor technology. Again, the numbers given are tos qualitative assumptions.rio (c) it is assumed that the MTRs efciency may beto 180% by e.g. a more active catalyst, higher averagere or elevated pressure.

are shown in Table 1. Striking on the one hand is acrease in reactor efciency considering the productactor volume for scenario (b) and (c). On the otherver, the economic potential in view of the total processited. Thus, scenarios (a), (b) and (c) yield production%, 88%, and 93%, respectively, compared to the con-rocess. The signicant increase of reactor efciency isby a relatively low but typical contribution of reactorn costs to the total production costs. Although 5% totalefciency increase is already very signicant for such aess, the uncertainty of the numbers based on the roughs as well as the technical issues displayed in Table 1s of the still immature technology have to be taken intoon.such a technology to realization several challenges havesedwith respect to the strong requirementsof chemicalustry regarding operational availability and reliability.ufacturing technology is required that yields cost ef-eliable reactors with the complete implementation ofured features and a volume suited for full scale produc-ould be addressed best by concepts based on alreadyhnologies used in heat exchangers. Second, efcienthniques have to be developed that lead to stable andst layers. Promising concepts are published in Ref. [16].

332 S. Becht et al. / Chemical Engineering and Processing 48 (2009) 329332Ta

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4. Conclus

From ansents a clasprocess andthe rate of aprocess indindustrial sis very higmeans thatnon-provenintegrated mand developbreakthrouchemical phere from timproveme

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An industrial view of process intensificationIntroductionInnovation opportunities within the chemical industryCase study: catalytic wall reactorConclusionReferences