DD270296A1 - PROCESS FOR PREPARING LOW OLEFINES - Google Patents

Abstract

The invention relates to a process for the preparation of lower olefins by joint conversion of methanol and hydrocarbons to Fe / Al-containing zeolites, which have a low coking activity and thus a higher reaction time for the above reaction and high molar olefin yields at elevated reaction temperatures.

Description

In summary, it should be noted that in the inventive common conversion of methanol and Hydrocarbons with iron and aluminum-containing zeolitic catalysts significantly lower amounts of coke on the Catalyst deposit and thus at approximately constant olefin yield longer catalyst life

let realize.

This is an essential contribution to the solution of this problem in the case of catalysts which under the reaction conditions of

common conversion of methanol and hydrocarbons work.

The present invention is further illustrated by the following examples. Additionally, examples are common Conversion of methanol and hydrocarbons to conventional Al or Fo-containing zeolites listed for comparison. exemplary For the common conversion of methanol / hydrocarbon mixtures was a fixed bed reactor made of quartz with a

internal diameter of 30 mm used, which is electrically heated. The quartz tube heater was split in three to accommodate different temperatures for the preheat, reaction and reheat zones.

The catalyst, which was placed in the reaction zone, was mixed over metering devices and preheated

e heated methanol vapor / hydrocarbon mixture fed continuously. The exhaust gas leaving the reactor was analyzed by conventional on-line quantitative gas chromatography.

The catalyst used was a Fe / Al zeolite with ZSM-5 structure in the Η-form. The Fe: Si ratio was 1:60, dv. AkSi ratio also 1:60. It was used pure methanol, and served as a hydrocarbon techn. η-butane (about 92% n- and 8% i-butane). The individual experimental parameters, conversions and molar and space-time yields are shown in Table 1. The

indicated yields refer to CH _{2 used} from methanol and n-butane.

Examples 1 and 2 I 1 7.5 g 3h 1h 3h 2 , 5g 3h 68O ⁰ C 100 100 100 600 ° C 100 Temp. 2.4: 1 63 63 56 2.4: 1 24 MeOH / KW 2.3 76 76 70 2.3 51 vvh 15ml & 15ml £ 7 amount of catalyst 1h 28.3 29.9 27.2 1h 13.1 t 100 0 0 0 100 2.6 To "oh 64 31.9 31.3 29.6 26 20.7 Uc. 77 178.6 193.8 163.9 52 103.5 Uch, 4h Yields (% by mass CH ₂ ! 30.5 2.5% deseinges.C 0.3% of the C used 14.7 1.9% deseinges.C C ₂ -C ₄ = 0 3h 10h 0 3h BTX 31.1 20.2 CH ₄ 192.6 114.5 RZAch: - 2h MeOH / KW 2.5: 1 (molar ratio) 1h flash duration vvh lh " ¹ ] 2.5 Koksirmnge reaction time Amount of catalyst 14ml ^ 7g 10h Example 3 t 98 Temp. 680 ° C UMeOH% 33 % Uc. 57 ₁ % Yields (wt.% CH ₂ ) 20.2 C ₂ -C ₄ = 0.9 8TX 21.8 CH ₄ 128.7 RZA (^ - C ₁ = flash duration coke reaction time

Examples 4 to 7 (Comparative Examples) In Examples 4 to 7, the following catalysts were used under the conditions given in Examples 1 to 3

worked.

Examples 4 and 5: ZSM-5 type high silica containing zeolite with a synthesis module of 55 Examples 6 and 7: Fe-containing zeolite of ZSM-5-γγρ with a ShFe ratio of 15 Examples 4 and 5

Temp. 680X 3h I5 6 600X 3h MeOH / KW 2.7: 1 98 2.7: 1 82 vvh 2.8 30 2.8 0 amount of catalyst 52 33 t UMaOH 19.1 9.7 Ukvv 30 ml of A 23 g 1.2 30ml £ 23g 1.1 UCH, 1h 22.1 1h 11.7 Yields (wt.% CH ₂ ) 99 289.0 92 129.4 C ₂ -C ₄ = 53 2 BTX 69 2.9% of the C used 38 1.3% of the CH ₄ put C RZAC-c-411.6 27.2 3h 12.1 3h flash duration 2.2 5.1 Koksmenue 27.3 13.3 7 411.6 151.3 reaction time 4h 2h Examples 6 and 7 Fe / Si = 1: 1

MeOH / KW

amount of catalyst

630X

4: 1

3.3

600 4: 1 3

Yields (wt.% CH ₂ )

RZAc ₁ -C, -

flash duration

coke

reaction time

1h 100

40

69

17.1 0

26.9 146.5 2h 2.8% of the C used

1h

1h 98 2 49

11.6 0

26.3 110.6 40 min

2.4% of the C 1h used

Claims (2)

1. A process for the preparation of lower olefins by co-conversion of methanol and gaseous and / or liquid hydrocarbons, characterized in that the reaction at ratios of 10: 1 to 1: 1 to iron and aluminum atoms containing zeolites with ZSM-5 structure , carried out at elevated temperatures in the range of 500 ⁰ C to 800 ⁰ C and at a load of 0.5 to 7vvh. 2. The method according to claim 1, characterized in that the ZSM-5 type zeolites used have a Fe: Si ratio of 1:25 to 1: 250 and an Al: Si ratio of also 1:25 to 1: 250 respectively. Field of application of the invention The invention relates to a process for the preparation of lower olefins by joint conversion of methanol and hydrocarbons, which is characterized by increased olefin yield and longer catalyst life. Characteristic of the known state of the art The combined reaction of methanol and hydrocarbons uses zeolites containing ZSM-5-γgamma. A drawback of the zeolites used is their rapid decalcification by blocking active sites of coke deposits. Another disadvantage lies * in the short life caused by coking and deactivation. Ferrous zeolitic catalysts are z. B. from DD-WP 232841 and u. a. also from J. Catal. 98 (1986) 491 and Zeolites 6 (1986) 253. In these zeolites, the aluminum atoms on their lattice positions are completely replaced by iron atoms. These iron-containing zeolites catalyze z. For example, the conversion of alcohols into oil-rich hydrocarbon mixtures and show a longer lasting catalytic activity relative to aluminum-containing zeolites. A disadvantage of the use of these zeolitic catalysts for the joint conversion of methanol and hydrocarbons is the too low cleavage activity for the hydrocarbons to be used, which is far below that of aluminum-containing zeolitic catalysts. DD-AP 232063 describes iron-containing zeolites of the mordenite type which, in addition to iron, may also contain small amounts of aluminum atoms on the lattice positions. However, the aluminum of these zeolites derives only from impurities of other oxide constituents or from the mordenite-type seed crystals used in the synthesis of the zeolites. Furthermore, the described zeolites of this type are unsuitable for co-conversion of methanol and hydrocarbon because of the reaction conditions to be used. Object of the invention The aim of the invention is to achieve at ier common conversion of methanol and hydrocarbons, a longer activity of the catalysts and higher yields of lower olefins. Explanation of the essence of the invention The invention has for its object to provide suitable catalysts for the joint conversion of methanol and hydrocarbons, which have a longer catalytic activity in relation to the known aluminum-containing zeolites of the ZSM-5 type and simultaneously allow higher C ₂ -C ₄ -Olefinausbeuten. According to the invention, the object is achieved by the use of selectively synthesized zeolitic catalysts of the ZSM-5 type which simultaneously contain Fe and Al atoms and which are distinguished both by a high catalytic activity in the methanol and in the hydrocarbon conversion. As catalysts for the joint reaction of methanol and hydrocarbons Fe and Al atoms containing zeolites are used with ZSM-5 structure. These zeolites can have Al: Si ratios of 1:25 to 1: 250 and Fe: Si ratios of 1:25 to 1: 250 as well. An advantage of this zeolite composition with ZSM-5 structure is its high thermal stability (up to about 900 ⁰ C). Surprisingly, the use of these Fe / Al-containing zeolites shows a significantly higher cleavage activity with respect to the hydrocarbons used in the co-conversion of methanol and hydrocarbons than is known from aluminum-containing or only iron-containing zeolites of the ZSM-5 type. In this case, due to the classification of Fe cations on certain lattice sites at the same time a much longer service life of the catalyst can be achieved at the same time higher yield of lower olefins. The amount of coke deposited during the reaction on the zeolite is much lower than that of conventional zeolites already described and thus results in the higher catalyst life. It also follows that the reaction cycles can take place in longer time intervals, d. h "decoking be necessary only at longer intervals. Another advantage of the present invention, as mentioned above, is that the Fe / Al zeolites can achieve higher molar olefin yields than conventional Al zeolites. The high molar olefin yields remain constant over longer reaction times.