NZ203293A

NZ203293A - Production of tert-butyl alkyl ethers in the presence of butadiene

Info

Publication number: NZ203293A
Application number: NZ203293A
Authority: NZ
Inventors: F Ancillotti; E Pescarollo
Original assignee: Snam Progetti
Priority date: 1982-03-12
Filing date: 1983-02-15
Publication date: 1984-12-14
Also published as: HU196351B; PL240765A1; CA1205824A; DE3308736C2; FR2523121A1; AU559931B2; DK65683A; CS232749B2; LU84665A1; PT76375B; BE896127A; KR860001359B1; NO156606B; GB2116546A; CS149383A2; IT1150678B; TR21654A; FR2523121B1; DK65683D0; PH19851A

Abstract

In producing t-butyl alkyl ethers by etherifying with aliphatic alcohols isobutene in a hydrocarbon feedstock containing butadiene in addition to the isobutene, the increase in the pressure drop in the etherification reactor(s) that is due to the butadiene is eliminated by feeding the reactants from the bottom upwards. The reactors preferably contain an acidic ion-exchange resin catalyst.

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number £03293 203293 P:ic-mC'/ Dztz!?}: .. !R. ?, •. Q~...-;.'rSjjz T; "jc'Tl^ction Filed: f-. --.C07C^3' C01 CM-1 , w DEC 19W" 'js; cats on Ds'is: . . .T. .0. Jcurna?, fjo: ..... ...... rrr^ tit, ^tNT 0/cjf \5f s££CBV^ NEW ZEALAND PATENTS ACT, 1953 No.: Date: COMPLETE SPECIFICATION PROCESS FOR PRODUCING TERT. BUTYL ALKYL ETHERS IN THE PRESENCE OF BUTADIENE kl We, SNAMPROGETTI S.p.A. , a. company organised, und.er the laws of the Italian Republic, of Corso Venezia 16 , Milan, Italy, hereby declare the invention for which ? / we pray that a patent may be granted to mst/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - (followed by" page la) 9 f>TC"7 Q. M '"r J -GAS6-W3— DESCRIPTION This invention relates to a process for producing tert.butyl alkyl ethers in the presence of butadiene. The reaction of addition of alcohols to tertiary olefins such as 5 isobutene to produce tert.butyl alkyl ethers is an exothermic reaction which is acid-catalysed. In the presence of suitable catalysts such as macroporous ion exchange resins, the reaction proceeds to equilibrium in times which are of industrial interest, even at relatively low ternper-10 atures (iH5-50OC). It is known that it is not necessary to operate with high purity isobutene, and instead any cut which contains it is suitable, as the alcohol addition takes place selectively to the double bonds which engage a tertiary carbon atom. Those cuts originating from 15 catalytic cracking and those originating from steam cracking, these latter either before or after extracting the butadiene, are particularly suitable. When using as olefin feedstock the fraction from catalytic cracking or that from steam cracking after extracting the butadiene, 20 and using methanol or ethanol as the alcohol and a sulphonic macroporous resin type Amberlyst 15 or Lewatit SPC 108 as the catalyst, the reaction can be used industrially within a wide range of reactor designs and operating conditions directed towards optimising the conversion of one or other of the reactants. In 25 these cases, high selectivity is always obtained, together with good performance of the catalyst both in terms of catalytic activity and life. 2^, 1"y "■*£ **!r ; -J '■< " ,J - 2- When operating with an olefin cut with a high butadiene content, such as the cut from steam cracking before extracting the butadiene, the operating conditions must be accurately defined in order to allow a butadiene recovery exceeding 98-99%• In particular, it is necessary to maintain a strict relationship between the temperature and spacial velocity as described in USA Patent ^,039»590. It has however been noted that when carrying out the isobutene etherification reaction in the presence of butadiene in a tubular reactor containing a macroporous resin, and feeding the reactants from the top downwards in the normal manner, an increase in pressure drops takes place with time, even when operating under conditions which allow a high butadiene recovery of^ 99%i and in addition a slight conversion fall-off. However, an identical test carried out with a butadiene-free cut shows neither pressure drop increases nor conversion reductions. It has been surprisingly found, and constitutes the subject matter of the present invention, that by feeding the butadiene-containing feedstocks so that they flow from the bottom upwards, under slight bed expansion conditions, the pressure drops remain constant with time. The process according to the present invention consists of producing tert.butyl alkyl ethers by reacting the isobutylene of a hydrocarbon feedstock which also contains butadiene at concentrations of between 10 and 70% by weight, with one or more aliphatic alcohols, preferably methanol or ethanol, in one, two or more reactors, preferably in series, and is characterised in that the - 3 - reactants (hydrocarbon feedstock containing butadiene and alcohol or alcohols) and the reaction products flow through the reactor or reactors filled with macroporous acid ion exchange resin catalyst, from the bottom upwards. 5 In addition to that stated regarding the ascending direction of' flow of the reactants and reaction products, it is important to note that the linear velocity of the reactants through the reactor or reactors varies from 0.5 to 2 cm/sec. and the temperature in the reactors lies between 50 and 6o°C,preferably between 50 and 55°C. 10 Some examples are described hereinafter for the purpose of better illustrating the invention, but these must in no way be considered as limitative thereof. EXAMPLE 1 A cut having the following composition: 15 Propylene 0.46% by weight Isobutane 6.87% by weight n-butane 11.80% by weight Butene-1 11.39% by weight Isobutene 30.19% by weight 20 Butene-2+ 3.25% by weight Cis butene-2 1.55% by weight Butadiene 3^.43% by weight is mixed with methanol such that the molar isobutene/methanol ratio is equal to O.85, and the mixture is fed at a throughput of 14 l/h 25 and a temperature of 50°C through two reactors connected in series, having a total capacity of 4.5 litres and filled with 4 litres of catalyst. The catalyst is a macroporous sulphonic resin with an - 4 - 2 4** "V ^ fy f • ** ^ ^ 10 exchange capacity of 4.8 meq H+/g dry. The reactants flow from the bottom upwards. The linear velocity is 1 cm/sec. The conversion and pressure drops with respect to time are as follows: - Time hours 24 500 2000 2 - A. P 1st reactor kg/cm 0.2 0.2 0.2 2 - A P 2nd reactor kg/cm 0.2 0.2 0.2 - % MTBE by weight 38.1 38 38 - % dimers and codimers by weight 0.05 0.05 0.05 - % butenyl ethers by weight 0.2 0.15 0.2 - isobutene conversion 96.6 96.4 96.4 - butadiene recovery ^99 ^99 ^99 - P represents pressure drop. 15 EXAMPLE 2 (comparative) The feedstock described in the preceding example is fed under the same temperature and spacial velocity conditions to the two reactors connected in series, but in such a manner that the flow direction of the reactants is from the top downwards. 20 At the beginning of the test, the results are analogous to those of the preceding example, but as time passes a progressive pressure drop increase and a slight conversion fall-off are observed. -Time hours 24 500 2000 2 - A. P 1st reactor kg/cm 0.3 0.4 1.5 2 - ^ P 2nd reactor kg/cm 0.3 0.5 1.8 % MTBE by weight 38 37.9 36 - % dimers and codimers by weight 0.1 0.1 0.05 </div>

Claims

<div class="application article clearfix printTableText" id="claims"> 2 Am <*:■' .«W> Jf;- 5 _;- % butenyl ethers by weight 0.2 0.2 0.2;- isobutene conversion 96.4 96.1 91.3;- butadiene recovery ^>99 ^99 ^>99 EXAMPLE 3 (comparative);Methahpl is added to an olefin cut containing 35% of isobutene and 0.2% of butadiene by weight, such that the molar isobutene/methanol ratio, is O.85.;The.mixture is fed at a throughput of l4 l/h and a temperature of 50°C to the two reactors connected in series, the flow direction being from the top downwards. In the absence of butadiene, no pressure drop increase or conversion fall-off with time are observed.;- Time hours;24;500;2000;2;-A P 1st reactor kg/cm;0.3;0.3;0.3;2;- A- P 2nd reactor kg/cm;0.3;0.3;0.3;% MTBE by weight;43.1;42.9;43;- % dimers and codimers by weight;0.3;0.3;0.2;- isobutene conversion;96.8;96.6;96.6;- 6 -;203293;WHAT WE CLAIM IS:;1) A process for producing tert.butyl alkyl ethers by reacting the isobutylene of a hydrocarbon feedstock, which also contains butadiene at a concentration of between 10 and 70% by weight, with one or more aliphatic alcohols,;in one, two or more reactors,;characterised in that the reactants and the reaction products are made to flov; from the bottom upwards through the reactor or reactors.;2) A process as claimed in claim 1 wherein said one or more aliphatic alcohols are selected from the group comprising methanol and ethanol.;3) A process as claimed in claim 1, characterised in that the reactants have a linear velocity of between 0.5 and 2cm/sec.;4) A process as claimed in claim 1, characterised in that the temperature in the reactor or reactors lies between 50 and 6 0°C.;5) A process as claimed in either claim 1 or claim 4 wherein the temperature in the reactor or reactors lies between 50 and 55°C.;6) A process as claimed in any one of the preceding claims wherein said reactors are in series.;By y^/the-r r!s»* A. J. PARK T.0,V ;.u SEP 1984 </div>