CA1092167A - Manufacture of light olefins - Google Patents

Abstract

MANUFACTURE OF LIGHT OLEFINS
ABSTRACT OF THE DISCLOSURE
A catalytic process for converting an organic charge consisting essentially of methanol, dimethyl ether or mixtures thereof, together with at least about 0.25 moles of water per mole of said organic charge, to a hydrocarbon product rich in ethylene and propylene which comprises contacting said charge under conversion conditions including a temperature between 500°F and about 1000°F, a pressure from about 0.1 to 30 atmospheres and a weight hourly space velocity of between about 0.1 and about 30 with a catalyst comprising a crystalline aluminosilicate zeolite of the orionite-offretite family.

Description

;7 1. Field o~ the''Invention.

This invention relates to a process for the conversion of a mixture of (l) methanol, dimethyl ether or mixtures thereof and (2) water to light olefins in the presence of a crystalline aluminosilicate zeolite of the erionlte-offretite family.

2. Description of the Prior Art.

U.~. 3,036,134 to Mattox discloses conversion of methanol to a reaction product containing water and dimethyl ether in the presence of a sodium or calcium crystalline aluminosilicate zeolite catalyst.
U.S. 3,529,033 to Frilette and Weisz discloses dehydra-tion of a normal alkanol of three to six carbon atoms to an olefin, utilizing a sodium or cà~cium crystalline aluminosilicate zeolite catalyst ha~ing uniform interstitlal dimensions sufficiently large to admit the alkanol charge and to permit egress therefrom of the ole~in product.
The prior art, typified by the above patents, has, neither disclosed nor recognized the advantages of a process for selectively converting a mixture of (1) methanol, dimethyl ether or mixtures thereof and (2) water to C2-C3 olefins utilizing the crystalline aluminosilicate zeolite catalyst described herein.
As those in the art are aware, a remarkable growth in the production of synthetic flbers, platics and rubber has taken place in recent decades. Their growth, to a very large extent, has been supported and encouraged by an expanding supply of inexpensive petroleum ra~ materials such as ethylene and propylene. Increasing demand for these light olefins has, from time to time, led to periods of shortage, either due to a diminished supply of suitable feedstocks or to limited process-ing capacity. In any event, it is considered highly desirable to provide efficient means for converting raw materials other than petroleum to light olefins.

SUMMARY OF THE INVENTION

In accordance with the present invention, there has been discovered a process which selectively produces valuable light olefinic hydrocarbons. The present process involves con-version of an organic charge consisting essentially of methanol, dimethyl ether or mixtures thereof together with at least about 0.25 moles of water per mole of organic charge by contact at elevated temperatures with a catalyst comprising a crystalline aluminosilicate zeolite of the erionite-offretite family.
~t has been found that use of such zeollte catalysts in combination with added water af~ord a substantially higher efficiency and selectivity for ethylene and propylene production over corresponding use of similar crystalline alumlnosilicate zeolites in the absence of added water. It has further been found utilizing the specified crystalline aluminosilica~e zeolite catalyst described herein that the C2-C3 olefin content of the reaction product preferably constitutes a ma~or proportion of such reaction product~ The latter is substantially devoid - of aromatic hydrocarbon content and contains, as a result of employing the specified catalyst, less than 20 weight percent, and preferably not more than 10 weight percent, of methane.

The methanol feedstock may be manufactured from synthesis gas, i.e., a mixture of CO and H2, from coal or may be produced by fermentation.
The present process comprises conversion of methanol, dimethyl ether or mixtures thereof together with 0.25 to 40 moles of water per mole of charge in the presence of the specified catalyst at a temperature between about 500F. and about 1000F. at a pressure between about 0.1 and about 30 atmospheres and preferably at atmospheric pressure utilizing a weight hourly space velocity (W~SV) between about 0.1 and about 30 and preferably between about 1 and about 10, said operating conditions being selected to produce olefins boiling below C5 hydrocarbons. The WHSV is based upon the weight of zeolite in the catalyst composition. The effluent is separated and distilled to remove the desired products of light olefinic hydrocarbons. Any unreacted charge may be recycled for further reaction.
DESCRIPTION OF SPECIFIC EMBODIMENTS

It is contemplated that an organic charge consisting essentially of methyl alcohol, dimethyl ether or mixtures thereof, together with at least about 0.25 moles of added water per mole of organic charge may be used as feed to the process of this invention. Such feed, in accordance with this invention, is brought into contact, under the aforenoted conversion conditions, with a bed comprising particle-form catalyst containing a crystalline aluminosilicate zeolite of the erionite-offretite family.
Included within this group of zeolites is erionitet both .~

C~Z~ 7 synthetic and natural, offretite, both synthetic and natural, zeolite T and zeolite ZSM-34. These zeolites have the common characteristic of possessing X-ray diffraction patterns which are substantially the same or similiar to those of erionite and offretite.
Zeolite T is described in U.S. 2,950,952.
Zeolite ZSM-34 and its synthesis are subject matter of copending Canadian application Serial No. 288,396 filed October 11, 1977. ZSM-34 is a unique crystalline alumino-silicate zeolite, belonging to the erionite-offretite family, having the composition, as synthesized, and after drying of:

(0.5-1.3)R20 : tO-0.15) Na20 : (0.10-0.50) K20 : A1203 : X SiO2 where ~ is the organic nitrogen-containing cation derived from choline [(CH3)3 NCH2CH20H] and X is 8 to 50, preferably 8 to 30 and still more preferably 8 to 20. This zeolite, ùnlike other members of the erionite-offretite family, appears to have a tabular morphology and the capability, after calcination at 1000F. for at least a period of time to remove the organic cation of sorbing at least 9.5 weight percent of n-hexane, at ambient temperature and a n-hexane pressure of 20 mm. which is higher than that for any other known offretite or erionite.
ZSM-34 is characterized by an X-ray powder diffraction pattern as set forth in Table 1 below:

~ILO~ 167 O Relative 2~ D(A) Intensity 7.68 11.5 + .2 VS
9.62 9.2 + .2 ~t 11.67 7.58 + .15 M
13.39 6.61 + .13 S
14.01 6.32 + .12 W
15.46 5.73 + 11 M
16.57 5.35 + .10 W
17.81 4.98 + .10 W
19.42 4.57 + .09 S-VS
20.56 ~.32 + .o8 VS
21.36 4.16 + .08 W
23.35 3.81 + .07 S-VS
23.79 3.74 ~ .07 VS
24.80 3.59 + ,o7 S-VS
27.02 3.30 + .06 M-S
28.33 3.15 + .06 M
30.62 2.92 + .05 W
31.41 2.85 + .05 VS
31.93 2.80 + o5 W
33.50 2.67 + .05 W
35.68 2.52 + .05 W
36.15 2.48 + .o5 W-M
38.30 2.35 + .04 W
39.49 2.28 + .04 1~

The intensity in the above Table is expressed as follows:

Relative Intensity lO-OI~Io VS (Very Strong) 60-100 S (Strong) 40-60 M (Medium) 20-40 W (Weak) 0-20 Thls zeolite, as synthesized, may be calcined to remove the organic co~stituent (R20) and/or ion exchanged to replace the alkali metal ions with hydrogen ion precursor and/or other metal ions, particularly metals from Groups IB, II, III, ~II~, VIII andthe rare earth metals with only minor changes in the X-ray characterizatlon and sorption properties.
The calcined and ion exchanged product is catalyt~cally active ZSM-34 useful in the process of this invention.
ZSM-34 can be suitably synthesized by preparing a gel reaction mixture ha~ing a composition, in terms of mole ratios of oxldes, falling within the following ranges:

Broad Preferred SiO~/A1203 = 10-70 10-55 OH-/SiO2 = C.3-1.0 o.3-0.8 H20~0H 3 20-100 20-80 K20~20 = 0.1-1.0 0.1-1.0 R~R-~+M+ = 0.1-0.8 0.1-0.5 ~here R+ is choline ~(CH3)3.N-CH2CH20H] and M ls Na~K and maintainl~g the mixture until crystals of the zeolite are formed. OH- is calculated from inorganic base not neutralized by any added mineral acid or acid salt. Resulting zeolite crystals are separated and recovered. Typical reaction conditions consist of heating the foregoing reaction mixture to a temperature of 3Z~G7 from about 80C. to about175C. for a period of tlme of from about 12hours to 200 days. A more preferred temperature range is from about 90 to about 160C. with the amount of tlme at a temperature in such range belng from about 12 hours to 50 days.
The resulting crystalllne product is separated from the mother liquor by filtration, water washing and drying, e.g., at 230F for from 4 to 48 hours. Milder conditions may be employed, i~ desired, e.g., room temperature under vacuum.
ZSM-34, when employed either as an absorbent or as a catalyst in a hydrocarbon conversion process, should be at least partially dehydrated and the organic cation at least partially removed~ This can be done by heating to a temperature in the range of 200to 750C. in an atmosphere such as air, nitrogen, etc. and at atmospheric or sub atmospheric pressure for between 1 and 48 hours. Dehydration can also be performed at lower temperatures merely by placing the catalyst in a vacuum, but a longer time is required to obtain a sufficient amount o~
dehydration.
The composition of ZSM-34 can be prepared utilizing materials which supply the appropriate oxides. Such composi-tions include, for example, sodium aluminate, alumina, sodium silicate, silica hydrosol, silica gel, silicic acid, sodium hydroxide, aluminum sulfate, potassium hydroxide, potassium silicate~ and choline. It will be understood that each oxide component utilized in the reaction mixture ~or preparing ZSM-34 can be supplied by one or more initial reactants and they can be mi~ed together in any order. The reaction mixture can be prepared either batchwlse or continuously. Crystal size and crystallization time-of the ZSM-34 composition will vary with the nature of the reaction mixture employed.

As aforenoted, other erionite-offretite type zeolites, whlle less preferred than ZSM-34, may be employed in the process described herein. Such zeolites include erionite and offretite, which may be elther in the naturally occurring form or synthetic.
In the latter form, the cation may comprise an alkali or alka-line earth, or may be an organic cation, e.g., tetramethyl-ammonium or benzyl tetramethylammoni~m. The latter, upon calcin-ation are converted to the hydrogen form.
The zeolites useful in the conversion process of this invention generally have at least lO percent of the cationic sites thereof occupied by ions other than alkali or alkaline earth metals. Typical but non-limiting replacing ions include ammonium, hydrogen,rare earth, zinc, copper and aluminùm. Of ; this group, particular preference is accorded ammonium, hydrogen, rare earth or combinations thereof. In a preferred embodiment, the zeolites are converted to the predomlnately hydrogen form, either by calcination of an organic cation form, as indicated above and~or by replacement of the alkali metal or other ion originally present with hydrogen ion precursors~ e.g., ammonium ~0 ions, which upon calclnation yield the hydrogen form. This ex-change is conveniently carried out by contact of the zeollte with an ammonium salt solution, e.g. ammonium chloride, utilizing well known ion exchange techniques. The ex~ent of replacement is such as to produce a zeolite material in which at least 50 per-cent of the cationic sites are occupied by hydrogen ions.
In practicing the desired conversion process, it may be desirable to incorporate the above-described crystalline aluminosilicate zeolites in another material resistant to the temperature and other conditions employed in the process. Such matrix materials include synthetic or naturally occurring sub-stances as well as inorganic materials such as clay, silica and/or metal oxides. ~he latter may be either naturally occur-ring or ln the form of gelatinous precipitates or gels including mixtures of sllica and metal oxides. Naturally occurring clays which can be composited with the zeolite lnclude those of the montmorillonite and kaolln famllies, which families include the sub-bentonites and the kaolins commonly known as Dixie, McNamee-Georgia and Florida clays or others in whlch the main mineral constituent is halloysite, kaolinlte, dlcklte, nacrlte or ana-uxlte. Such clays can be usedin the raw state as orlglnally mined or lnltially sub~ected to calcination, acid treatment or chemical modiflcatlon.
In addltion to the foregoin~ materials, the small pore zeolites employed hereln may be compounded with a porous matrlx materlal, such as alumlna, sillca-alumina, sllica-magnesla, slllca-zirconia, silica-thoria, sllica-beryllia, silica-titania, as well as ternary combinationslsuch as silica-alumina-thoria, sillca-alumina-zirconia, silica-alumina-magnesia and sllica-magnesia-zirconla. The matrix may be in the form of a cogel.
The relative proportions of finely clivlded zeolite and lnorganic oxide gel matrix may vary widely with the zeolite content rang-ing from between about l to about 99 percent by welght and more usually in the range of about 5 to about 80 percent by weight of the composlte.
In the process of converting methyl alcohol and/or dimethyl ether to hydrocarbons, water is a ma~or product of re-action. In accordance with the present lnvention, it has been found that the addition of water to the initial methanol and/or dimethyl ether feed serves to enhance the selective production f C2 and C3 olefins. Thus, it has been found that the addition of water to the noted feed is particularly beneficial in direct-lng the conversion toward light olefin (C2 and C3) production and away from the formation of C4+ hydrocarbons. In so doing, ~32~fi7 the initlal presence of water in the reaction mixture, also has been found to lengthen the cycle life of the catalyst. Wlthout being limited by any theory, lt is believed that this is due to a decrease in the rate of coke formation.
The amount of water added along with the organic charge of methanol and/or dimethyl ether is generally at least about 0.25 moles of water per mole of the organic charge. Preferably, the amount of water added is greater than about 0.5 moles of water per mole of organic charge. The amount of water initially added to the organic charge usually will not exceed about 40 moles per mole of said charge.
The process of this invention i5 conducted such that methyl alcohol and~or dimethyl ether conversion is carried out in the vapor phase by contact in a reaction zone, such as for example, a fixed~ fluidized or moving bed of catalyst, under effective conversion conditions. Such conditions include an operating temperature between about 500F. and about 1000F., a pressure between about 0.1 and about 30 atmospheres and pre-ferably atmospheric pressure and a weight hourly space velocity between about 0.1 and about 30 and preferably between about 1 and about 10. Carrier gases or diluents may be in~ected into the reaction zone su~h as, for example, hydrogen or nitrogen.
The methyl alcohol and/or dimethyl ether conversion process described herein may be carried out as a batch-type, seml-continuous or continuous operation utilizing a fixed, fluidized or moving bed catalyst system. A preferred embodiment entails use of a catalyst zone wherein the alcohoi or ether charge together with added water is passed concurrently or countercurrently through a fluidized or moving bed of particle-form catalyst. The latter after use is conducted to a regenera-tion zone wherein coke is burned from the catalyst in an oxygen-~32,~6"~

containing atmosphere, e.g., air, at an elevated temperature~
after which the regenerated catalyst is recycled to the con-ver~ion zone ~or further contact with the alcohol and/or ether water ~eed.
The product stream in the process of the invention contains steam and a hydrocarbon mixture of para~fins and oleflns, substantially devoid of aromatics. This mixture is particularly rich in light olefins, i.e., ethylene and propylene.
Generally, a ma~or fraction of the total olefins is ethylene plus propylene with the ethylene contact of the product exceed-ing the propylene content. Thus, the predominant hydrocarbon product constitutes valuable petrochemicals. The steam and hydrocarbon products maybe separated ~rom one another by methods well known ln the art.
lS In a preferred embodiment of the invention, the unconverted methanol and/or dimethyl ether, as well as at least part of the water in the product, are recycled to the reaction zone.
The following examples wlll serve to illustrate the process o~ this invention without limiting the same.

ZSM-34 was prepared by interacting the following solutions:
A. Caustic Aluminate 68.89 grams sodium aluminate (20 wt.% Na 43.1 wt % A1203 Balance H20 29.28 grams NaOH (77.5 wt.% Na20) 26.4 grams KOH 86,4% KOH
540 grams H20 B. Sllica Solution 780 grams Colloidal Silica sol (30 Wt. % SiO2) ~92~

C. Chollne Chloride 228 grams These were mixed together in a 2 liter autoclave addlng solution C to solution A and then adding solution B
followed by a 15 minute continuous mixing. The autoclave was then sealed, pressure-tested and then heated to and held at 300F. for 8 days. The contents were stirred continuously during the 8 day crystallization period.
The autoclave and its contents were cooled to room temperature and the crystalline product was filtered and washed.
On analysis the product was found to contain:
Na, wt % o.68 K, wt % 3.5g A1203 wt % 13.5 SiO2, wt % 78.5 N, wt % 2.5 The resulting ZSM-34 product had the following molar composition:
0.54 R20: 0.11 Na20 ~ 0.35 K20 : A1203 : 9-87 SiO2 The adsorption data for the product after calcining in air at 1000F. for 10 hours was as follows:
Cyclohexane, wt % 3.5 n-Hexane, wt % 9.6 H20, wt % 19.7 A sample of the calcined alkali ZSM-34 was further processed by contacting with~a 10 wt % NH4Cl solution for one hour at about 185F. using 10 ml. of solution for each gram of ZSM-34. A total of four contacts were made at these conditions followed by final filtration and water washing essentially free of chloride ion.
The product was dried at 230F. and calcined for 10 hours at 1000F. The residual alkali content as Na was 0.035 wt % while the residual X content was 1.47 wt %. This product had a surface area of 517 m/g and the following sorption 2~1~;7 capacity:
Cyclohexane, wt % 2.6 n-Hexane, wt % 10.0 H20, wt % 18.7 EXAMPL~ 2 A feed comprised of 30 wt % methanol and 70% water was passed over 2.0 grams of the catalyst of Example 1 at a rate of 7.7 ml per hour. The catalyst contained in a 15 mm outer diameter tubular glass reactor, had an axial bed length of 1-7/8 inches. The catalyst was air calcined in place at 1000F.
for one hour with an air flow of 10 cc/min. Nitrogen at a rate of 10 ccjmin wa~ passed over the bed for 10 minutes while the temperature dropped to 700F. The run conditions, temperature profile of the bed and the product analysis of reactor effluent samples taken at four different intervals during the run are set forth in Table 2 below.

IS~ O~ . .OO
,j ~Lr~ ~L~ N

a~o~I~o~ O~OO--~D~ ~ ~I O ~~~lr~3 ~ 1~ ~ ~3 ~3 ~ ~IL~

U~
IS~ Ll~ C~l ~0 ~IS~~ O ~D 3 ~ t--O O 0 3 N Ir\ ~ ~J

3 a2, ~S~ O ~1.. . . . . o . . . . . o ~U

LS~ O o O
t~ N ~0 ~I Ln~ 3 N

a) bO
h Nr~l 1~ S
~ I I C~
O ~1 ~1 'I ' .. a~
a) o h o ~ ~ -E s ~ g ~ ~ o ~: ~ o ,1 `- ~ ~ ~ ~ X ~ ~
o ~ o ~ S ~ 11 11 11 ~ ~ ~ ~ o ~ a~

o o E P~ ~ N N ~ ~r)3 3 IS~
E E ~I c/~ o o ~ ~ ~ o h 3~
Example 3 ZSM-34 was prepared by interacting the following solutions:
A. Caustic Aluminate Solution 22.96 grams NaAlO2 (43.1 wt % A12O3, 33.1 wt %
Na2O, 23.8 wt H2O) 9.76 grams NaOH (97.5%) 8.8 grams KOH (86.4%) 180 grams H2O
B. Colloidal Silica 260 grams (30 wt % SiO2) C. Choline Chlorlde 76 grams These solutions were mixed together by adding C to A then adding B and mixing for 15 minutes. The mixture was transferred to a polypropylene container and reacted at 210F for 32 days yielding a zeolite identified as ZSM-34.
A sample of the above alkali zeolite after flltering, washing~ and drying had the following molar composition:
0.07 Na2O : 0.36 K2O : 0.67 R2O : A12O3 : 10.2 SiO2 where R is the organic ion derived from choline chloride.
The adsorption capacity for a sample of the above product calcined (16 hrs. at 1000F) was:
Cyclohexane, ~t % 4.9 n-Hexane, wt % 10.3 H2O, wt % 20.9 The surface area for the calcined sample was 524 m2/g.
Another sample of the above alkali product was pro-cessed by calcining for 10 hours at 1000F and exchanged with a 10 wt % NH4Cl solution at 185F employing 5 one hour contacts.
After the final contact the exchanged product was filtered, water washed, dried at 230F, pelleted and sized 14-25 mesh and calcined for 10 hours at 1000F in air.

-10.C~Z~

~a~' Methanol at a rate of 4.0 ml/hour was passed over a 1 gram sample of the catalyst of Example 3 at a temperature of 700F. The effluent stream from the reactor was collected 5 between 1 and 2 hours on stream. The run conditions and product analyses are shown in Table 3.

Example 5 Addition of steam as a diluent improved the selectiv-ityfor ethylene. A charge solution comprised of 30% by weight of methyl alcohol and 70% by weight of water was passed over 1.0 gram of the catalyst from Example 4 at a rate of 3.6 grams per hour. The run was made at a nominal 700F. and atmospheric pressure. The catalyst bed had an axial bed length of 2-1/2 inches. The catalyst from Example 4 was calcined in place wlth an air flow of 10 cc/min at 1000F. for 5 hours followed by a 10 minute nitrogen purge of 10 cc/min while the reactor temper-ature dropped to 700~F. The temperature distribution of the bed after passing charge for two hours is shown in Table 2.
The effluent stream from the reactor was colleeted between 1 and 2 hours on stream. Run conditions and product analysis are shown in Table 4. In the run 72.2% of the methyl alcohol was converted of which 41.4% went to oxygen-free hydrocarbon product.
The selectivity for ethylene was 59.7%.

Table 3 Example 4 Example 5 Charge: MeOH MeOH/H20 Hours on Stream 2 2 Temp., F (nominal) 700 700 WHSV (Total) 2.0 3.6 of MeOH - 1.2 of Water - 2.4 Mole Ratio (H20/MeOH) - 3.4/1 Conversion of MeOH, wt. % 88.2 72.2 Product (wt. %) DME 36.9 3.9 Water (excludes water in charge) 40.3 54.7 Hydrocarbon Phase 22.4 41.4 Hydrocarbon Phase (wt. %) Cl 2.1 1.6 C2 - 42.5 59.7 C2 0.4 1.1 c3 = 26.1 23.6 C3 1.8 5.2 C4 = 6.7 5.8 C4 3.8 1.3 C5 = - 1.4 C5+ 16.5 0.3 ?2~
Example_6 A synthetic offretite was prepared as follows:
Into a solution comprising 92 grams sodium alumlnate, 112 grams sodium hydroxide, 277.6 grams potassium hydroxide and 1440 grams water were added 2142 grams colloidal silica sol and from a separate source, 131.2 grams of a 50% by weight aqueous tetramethylammonium chloride solution. The mixture was heated at about 212F. and within 5 days crystals formed. The crystals were separated from the supernatant liquid, washed, dried and then calcined 96 hours at 900F. in air. Chemical analysis of the product showed the following mole ratios:
R20(l) 0.31 Na2O 0.12 A1203 1.0 SiO2 7.9 ~1) R = (CH3)4N - tetramethylammonium.
This offretite was further processed by first heating at 1100F. for 6 hours and then base exchanged with 2520 ml of 5% NH4Cl solution at 180F. Four one hour contacts with fresh 5~ NH4Cl solution were employed. The mixture of solu5ion and offretite was stirred during the base exchange process. Follow-ing the base exchange treatment the o~fretite was then water washed free of chloride ion with 8 liters of water and air dried at 230F. This material contained o.o6 weight percent sodium.
A portion of this material was pelleted and sized to 14 x 25 mesh and then calcined ln air for 10 hours at 1000F. The adsorption properties o~ this material were determined. The product sorbed 9.7 weight percent cyclohexane determined at 25C. and under a pressure of 20 mm Hg, 10.1 weight percent normal hexane determined :
~ 2~

at 25C. and under a pressure of 20 mm Hg, and 21.9 weight percent water determined at 20C. and 12 mm Hg.

Example 7 Methanol at a rate of 3.8 ml per hour was passed over 1.0 gram of the catalyst of Example 6. The catalyst pretreatment and purge procedures are the same as described in Example 2.
The run conditions, temperature profile of the bed and product analysis of the reactor effluent collected between 1 and 2 hours on stream are described in Table 4. Of the 82.8% methanol con verted 2.4% went to oxygen-free hydrocarbon product. Ethylene was 20.2% of the hydrocarbon phase.

Example 8 A charge solution comprised of 30% weight of methanol and 70 weight percent of water was passed over 3.0 grams of the acld offretite of Example 6 at a rate of 8.9 gram per hour at atmospheric pressure. The 15 mm outer diameter tubular glass -reactor of Example 2 was used in this experiment. This experi-ment was run under conditions essentially ldentical to Example 2.
Data are shown in Table 4. The methanol was 91.8% converted of which 40.4% went to oxygen-free hydrocarbon product of which 28.9%
was ethylene. The ethylene yield per pass was 25 times greater than for Example 7.

Example 9 A synthetic offretite was prepared by interacting the following solutions:
Silicate solution: Q Brand~ 960 g.
KOH (88%) 119.5 g.
H2O 1050 g.

~lum solution: Al2(SO4)3'XH2O 100.5 g, KCl 107 g.
- H2O 550 g.
Tetramethylammonium chloride (50%) 128.6 g.
The above silicate and alum solutions were mixed in a Waring blender for 10 minutes. The resultant gel was aged at ambient temperatures for four hours, then was transferred to a 1 gallon autoclave. TMA Cl was added to the gel. The mixture was crystallized at 210F. with stirring for about 65 hours.
The product mixture was filtered, washed and dried. The product was TMA offretite, as shown by x-ray diffraction pattern. The crystal size of the product was 0.040-0.2 micron. The chemical composition was found to be:
Weight Percent S1O2 72.2 ~123 13.7 Na o.64 K 5.4 N o.87 C ~.76 Ash 87.5 The dried zeolite was precalcined at 1000F. in flowing N for 3 hours, followed by NH4NO3 exchange to reduce Na content in zeolite. The sample was sized into 14/20 mesh and air calcined at 1000F. for 3 hours. The final product was analyzed and found to contain 0.02% weight Na and 2.4% weight K.

Example 10 One gram of the offretite described in Example 9 was used in an experiment in which methanol was passed over this material under conditions essentially identical to Example 7.
Data are shown in Table 4. Of the 81.4% converted methanol 1.6%

went to oxygen-~ree hydrocarbon product.

Example 11 The methanol/H2O charge solution of Example 2 was passed o~er 2.0 grams of the catalyst of Example 9 at a rate of 7.8 ml per hour. The experimental procedure was the same as described in Example 2. Data are shown in Table 4. Of the 79.4% converted methanol 36.7% went to oxygen-free hydrocarbon product. Ethylene was 40.2% and propylene was 21.1% of thls hydrocarbon product.

Example 12 Synthetic tetramethylammonium offretite was prepared as follows:
Two solutions were made and interacted:
1. Alum Solution 67.6 g Sodium aluminate 102 g 50% TMA~l (tetramethylammonium chloride) 86.4 g NaOH ~97.1%) 213 g KOH (86.0%) 1083 g H2O
~F~ 2. Ludox~Colloidal Silica - 30 weight percent 20 ~ SiO2 - 1557 g.
These two solutions were mixed together in a Waring 81endor for 10 minutes, transferrecl to polypropylene jar, and allowed to crystallize in a steam bath at 210-212F. The re-action required 42 hours to form a highly crystalline zeolite identified as TMA offretite. The product was separated from the reaction mixture by filtration and washing, followed by drying at 230F.
The analyzed product had the following composition:
Na, wt % 0.95 ~, wt % 5.0 A12O3, wt % 13.8 SiO2, wt % 68.7 Molar ratios were:
0.15 Na2O : 0.48 K2O : 0.33 R2O A12O3 8.42 SiO2 where R = tetramethylammonium (TMA) ion.

`: :
~ ;7 The adsorption propertles were:
Cyclohexane, wt % 8.8 n-Hexane, wt %9.2 H2O, wt % 18.2 The above alkali zeolite was pre-calcined in N2 for 3 hours at 1000F., then base exchanged at room temperature with a 1 N NH4NO3 solution employing 10 ml/g of zeolite. The zeolite was contacted twice followed by water wash, air drying at 230F., pelleting and sizing. The catalyst was finally calcined for 3 hours at 1000F. prior to use in methanol conversion.
The final catalyst had a residual sodium content of 0.12 weight percent while the potassium content was 2.0 weight percent.

Example 1~

One gram of the TMA offretite of Example12was used in an experiment identical to Example 7. Data are shown in Table 4.~ The methanol was 83.2% converted of which 16.1% went to oxygen-free hydrocarbon product.

Example 14 The charge solution of Example 2 was passed over 2.0 grams of the catalyst of Example12 at a rate of 7.6 ml/hr. The experimental procedure was the same as described in Example 2.
Data are shown ln Table 4. 0f the 95.5% methanol that was con-verted 42.7% went to oxygen-free hydrocarbon product. Ethylene was 32.7% and propylene was 15.2% of this hydrocarbon product.

Exa~ple 15 Synthetic erionite was prepared by interacting the following solutions:
A. Sodium Aluminate Solution 98 2 g NaAlO2 (41.8 wt % A12O3, 33.1 2 208 g NaOH 97 wt ~
42.4 g XOH 85.5 wt %

B. Colloidal Silica 234 g Colloidal Silica 30 wt % SiO2 C. Benzyltrimethyl Ammonium Chloride 142 g 60 wt % solution These were mixed together adding C to A and then adding B. After mixing for 15 minutes the slurry was transferred to two polypro-pylene ~ars and reacted in a 212F. bath for 68 days. The crys-talline synthetic erionite product had the following composition:
Na, wt % 2.3 K, wt % 4.7 N, wt % 0.77 Al2o39 wt % 14.1 S~02g wt % 81.0 Ash 86.6 The adsorption capacity of a sample after calcination for lO
hours at 1000F. was:
Cyclohexane, wt % l.0 n-Hexane~ wt % 8.4 H20 16.6 m2/g was 447 The zeolite prepared above was calcined for lO hours at 1000F. and then contacted 4 times with 113 ml of 0.~ N NH4Cl solution at 190-195F; The exchanged zeolite was water washed essentially free of chloride ion, dried at 230F., pelleted and sized 14-25 mesh and then calcined Por 10 hours at 1000F. prior to use. The residual sodium content was 0.18 weight percent.

Example 16 Methanol at a rate oP 7~6 ml per hour was passed over 2.0 grams of a synthetic erionite described in Example 15. The experimental procedure was the same as described in Example 7.
Data are shown in Table 4. The methanol was 76.4% converted of which 6.1% went to oxygen-free hydrocarbon product.
-2)l Example 17 A methanol/water charge solution as described in Example 2 was passed over 2.0 grams of the catalyst described in Example 15 at a rate of 7.8 ml per hour at atmospheric pressure. The experimental procedure was the same as described in Example 2. Data are shown in Table 4. Of the methanol con-verted (84.8%), 39.3% went to oxygen-free hydrocarbon product.
- The hydrocarbon product contained 60.1% ethylene and 25.9%
propylene.

Example 18 Zeolite T was prepared in accordance with Example 1 of U.S. Patent 2,950,952. The resulting product had the follow-ing composition:

Na, wt % 2.07 K, wt % 8.18 A12~3, wt % 16.8 SiO2, wt % 67.7 Molar ratio of SiO2/A12O3 6.8 The sorption capacity of a sample calcined at 1000F. was as follows:

Cyclohexane, wt % 0.9 n-Hexane, wt % 2.0 H20, wt % 12.6 The above alkali zeolite was subsequently processed by calclning in air for 10 hours at 1000F. then exchanged for 2-4 hour contacts with 5 M NH4Cl at 180F. using 6 ml of solution per gram of zeolite. This treatment was followed by water washing essentially free of Cl ion, drying and recalcining for 10 hours at 1000F. The base exchange step was repeated again to reduce the residual alkali to low le~el. The water washed exchanged zeolite was air dried at 230F. 3 pelleted and sized 14-25 mesh and recalcined for 10 hours at 1000F.

i7 An analysls of the final catalyst showed the following composition:
Na, wt ~ 0. 075 K, wt % 1. 65 Al2O3~ wt % 18 . 7 SiO2, wt % 78. 8 Molar Ratio S12/A123 7. 2 The sorption capacity was as follows:
Cyclohexane~ wt % 0. 6 n-Hexane, wt % 5. 7 H2O, wt % 13.1 Surface area was 199 m2/g Example 19 The catalyst used here was prepared by the method des-cribed in Example 18 . Methanol at a rate of 7. 5 ml/hr was passed over 2 grams of this catalyst under conditions essentially the same as described in E~ample 7. Data are shown in Table 4. Of the 69.1% converted methanol only 2% went to oxygen-free hydro-carbon product.

Example 20 The catalyst sample used in Example 19 was removed from the reactor, placed in a crucible and calclned in air for 16 hours at 1000F. It was placed back into the same reactor, heated up in nitrogen to 700F. and a methanol/H2O charge solu-tion as described in Example 2 was passed over this 2.0 grams of catalyst at a rate of 7. 4 ml per hour. The experimental procedure was similar to that described in Example 2. Data are shown in Table 4. Of the 33% methanol converted, 20. 6% went to oxygen-free hydrocarbon product which was 54 . 4% ethylene and 25. 9% pro-pylene.

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~DS~ ;7 Example 21 This catalyst was prepared by calcining 243 grams of natural erionite (crushed and ground ore of Jersey Valley, Nevada) in a thin layer at 1200F. in a furnace. The calcined material was then exchanged at reflux temperature of 218F.
with 1200 ml. of 5 Molar NH4Cl solutlon per exchange. Two 2-hour exchanges were used followed by a wash with 2000 ml. of water after the second exchange.
The resulting wet cake was reslurried in 435.8 grams of 8.3 weight percent Ca(NO3)2 solution for 2 hours at 180F., followed by filtering, drying at Z25-250F., and recalcining for 1-1/2 hours in a thin layer at 1200F. in a preheated furnace.
The recalcined catalyst was then re-exchanged for 2 hours at a reflux temperature of 216F. with 1200 ml. of 5 Molar NH4Cl solution and washed with 2000 ml. of water.
A sample of the above hydrogen form of erionlte was dried at 230F. for 22 hours, pelleted and sized 14-25 mesh, followed with a calcination at 1000F. for 10 hours. This cata-lyst was used in evaluation of methanol conversion w~th and without added water under the conditions set forth in Table 5.

Example 22 In preparing the zinc form of the natural erionite described in the preceding Example, 73.4 grams of the above ammonium form as wet cake was slurried with 67 ml. of water and heated to 190 to 195F. To this was added 116 ml. of 2 Normal Zn(NO3)2 solution at 190-195F. The contact was continued for 4 hours at 210F., followed by filtering, washing with 500 ml. of water, drying at 225-250F., pelleting and sizing to 14-25 mesh. The 3o sized zinc erionite product was calcined at 1000F. prior to 2~

use in methanol conversion with and without added water. The conversion conditions and results obtained are set forth in Table 5 below.

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;7 It will be seen from the above examples that while ZSM-34 was 2 very effective catalyst for selectively converting methanol to C2-C3 olefi~ns, its selectivity was markedly improved by the presence of added ~ater to the methanol feed.
It is further to be noted that methanol was converted only slightly over two different samples of synthetic of~retite (Examples 7 and 10). The oxygen-free hydrocarbon product though small contained reasonable ethylene concentrations, e.g. 20.2 percent for Example 7. A third offretite sample gave a higher yield o~ oxygen-free hydrocarbon product with a somewhat dimin-ished (13.1 percent) ethylene concentration ~Example 13).
When a mixture of water (70%) and methanol (30%) was passed over these offretite samples under conditions of equal residence times, (total moles of charge per minute, i.e. water plus methanol, divided by volume of catalyst bed) ethylene/
propylene yields lncreased markedly (Examples 8, 11 and 14).
The relative increase in selectivity for producing ethylene per pass for these three samples are shown below.
- Relative Increase A. CH~OH O~er B. CH30H ~ H2O In C2 = Selectiv~
Of~retite Over Offretite ity Per Pass B - A
Example 7 Example 8 27 Example 10 Example 11 1~5 Example 13 Example 14 8 In each instance, the improved selectiv~ty factor is quite large.
The same trend was observed for synthetic erionite.
The improvement in ethylene selectivity per pass increased 9 times in going from no water (Example 16) to water dilution (Example 17). Similar trend l.~;as observed for Zeol~te T prep2red 3o in Example 18. The improvement in ethylene selectivit~ llsir.g th's zeol~te increased sixfold in going from no wa~er (Exar.ple 19) to ~rater dilution (Example 20).

-3~'-It is to be understood that the foregoing description is merely illustrative o~ preferred embodiments of the lnvention of which many variations may be made by those skilled in the art within the scope o~ the ~ollowing claims without departing from the spirit thereo~.

Claims (14)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for converting a charge of methanol, dimethyl ether or mixtures thereof to a hydrocarbon product rich in ethylene and propylene which comprises contacting said charge together with 0.25 to 40 moles of water per mole of charge at a temperature between 500°F.
and 1000°F., a pressure from 0.1 to 30 atmospheres and a weight hourly space velocity between 0.1 and 30 with a catalyst comprising a crystalline aluminosilicate zeolite of the erionite-offretite family.

2. A process according to Claim 1 wherein ethylene and propylene constitute a major proportion of said hydrocarbon product.

3. A process according to Claim 2 wherein the ethylene content of said product exceeds the propylene content.

4. A process according to Claim 1, 2 or 3 wherein the amount of water is greater than 0.5 moles per mole of charge.

5. A process according to Claim 1, 2 or 3 wherein unconverted methanol or dimethyl ether and at least part of said water is recycled.

6. A process according to Claim 1, 2 or 3 wherein said crystalline aluminosilicate has been thermally treated at a temperature of 200°C to 750°C.

7. A process according to Claim 1 wherein at least 10 percent of the cationic sites of said crystalline alumino-silicate zeolite are satisfied by ions other than alkali or alkaline earth metals.

8. A process according to Claim 7 wherein said other ions are hydrogen or hydrogen precursor.

9. A process according to Claim 1, 2 or 3 wherein said crystalline aluminosilicate zeolite is predominantly in the hydrogen form.

10. A process according to claim 1, 2 or 3 wherein said crystalline aluminosilicate zeolite is contained in a matrix therefor.

11. A process according to Claim 1, 2 or 3 wherein said crystalline aluminosilicate zeolite is erionite.

12. A process according to Claim 1, 2 or 3 wherein said crystalline aluminosilicate zeolite is offretite.

13. A process according to Claim 1, 2 or 3 wherein said crystalline aluminosilicate zeolite is zeolite T.

14. A process according to Claim 1, 2 or 3 wherein said crystalline aluminosilicate zeolite is ZSM-34.