AU499397B2 - Regeneration of vanadium-phosphorus catalyst complex - Google Patents

Description

FV I Forms I and 4 I

COMMONWEALTH OF USTRALIA

Patents Act 195241962

t q ICATION FOR A PATENT (Combined Form Convention and Non-Conventior 8516 6n75 ~OIL 'I'W CORPORATION, a_ corporation_ prganized nd 9, existing 'under the laws of the State of New York, V S V of 150 East 42nd Street, NwYrNsi.. United V. States of Amrerica, V a V

SV@0. 0 hereby apply for the grant of a Patent for an. invention REGENERATION OF VANADIUM-PHOSPHORUS CATALYST COMPLEX WITH *5 S ALKYL -PHOSPHATES 0 5 0

V* *0 0 S. which is described in the accompanying Complete Specification.

2. This application iq a Convention Application and is based on the application(s) for a Strike aut Para. 2. for ngn.i~cition patent or similar protection made- United States of America

on 11th, November, .19 74 numbered. 522,3921. and num bered and

on numbered.

0 9 S 3. My/Our address for service is: Care of COWIE, THOMSON CARTER Patent V 9* V Attorneys, of 343 Little Collins Street, Melbourne, Australia. 3000

D)ATE~D this 25th day of Augis t 19

COWIE, THOMSON CARTER

By:

Patent Attorneys for I~OBIL OIL CORPORATION

de Siai.nos to value of

To the Commissioner of Patents, aftehoJ COMMONWEALTH OF AUSTRALIA

WF~i;nz 7 abd 8 COMMOkNWE -TH OF AUSTRALIA COWIE, THOMSON CARTER Patents Act 1952-1962 Palot Attormeys F-E720 343 Li'!ic Collins Street Melbourne

Declaration in Support of CAn Application for a Patent (Combined Form Convention and Non-Convention)

0 gu*t.@ 06t tot 8.5.6 6M 75 cn lit support of thc Con vention* appliction maJe for a PCftfor an **a4QMVatI&e invention entitled. R~EE.RATI0N. OF VANADIUM-PHOSPHORUS CATALYST GOMPLRX WITH ALKXL ,PHIOSPHATES

IEDW'ARD, HATCH, VALANICE., .TRAD0MARK INTERNATIONAL PAT 4 2nd Street. New Yp. ,CORPORATION 1 .150 East 1w

do sr~emnly and sincerely declare as follows:- IW (or in the case of an application by a body corporate) 1. 1 am authorised by MO I I O P P.IO the applicant for the pt to make this declaration on its behalf.

3trtv out Nrs. 2. 2. The basic application(s) as defined by section 141 of the Act were made at 4 t Washington, P. C. in United States..of Ainerica on the. 11.th -day of November 19, 7.4. ,No. .522392.. by AN~THONY TIHEODORE J)URXICZ and LEWIS and on the -day of 19 .I and on tho -day of A9. I a I. by I

(or, where a person other than the inventor is the applicant) 3. AN1fHQNX-YTHWEODORE JUTCZQ3. A1dJ0LUQ. *TN.. Road and 59 Stockton Road, Kendall Park, New Jersey, United States of America, respectively

rcthe actuai inventor(s) of the invention and the facts upon which MOBIL OIL CORPORATION is........entitled to make the application are as follows:- The said Company is the assignee of' the invention from the said actual inventor(s)

204aa v 4, The basic application(s) referred to 'in paragraph 2 of this Declaration was the first were application(s) made in a Convention country in respect of the invention the subject of the application. DpiCLApEI) A.T: New York, State of New York, United States of America This: August 19, 1975 MOBIL OIL CORPORATION

BY

(11) AU-B 85166/75 j1 AUSTRALA,

(12) PATENT SPECIFICATION ABRIDGEMENT (19) AU (21) 85166/75 499,397 (22) 25.9.75 (23) 25.9.75 (24) 11.11.74 (31) 522392 (32) 11.11,74 (33) US (43) 31.3.77 (44) 12.4.79 (51) 2 C07C 51/18 C07C 51/20 C07C 57/14 B01J 23/22 B01J 27/18 (54) REGENERATION OF VANADIUM-PHOSPHORUS CATALYST COMPLEX (71) MOBIL OIL CORPORATION (72) JUREWICZ, A.T. YOUNG, L.B. (74) CM (56) 62325/73 481033 09.13 56572/73 471976 09,13 07.93 48840/72 468293 09.13 07.93 (57) CLAIM 1. A process for the vapor phase oxidation of alkanes naving from 4 to 10 carbon atoms, cycloalkanes having from 4 to carbon atoms, or mixtures comprising alkanes or cycloalkanes having from 4 to 10 carbon atoms to form maleic anhydride, in which the alkane, cycloalkane or mixture comprising the alkanes or cycloalkanes is contacted with a vanadium-phosphorus-oxygen catalyst complex promoted with zirconium, hafnium, chromium, iron lanthanum, or cerium, the catalyst being regenerated by contacting it during the vapor phase oxidation with an alkyl ester of orthophosphoric acid having the formula (RO) 3 P=0, wherein R is hydrogen or C 1 -C4 alkyl.

13/5

COMMONWEALTH OF AUSTRALIA Form

PATENTS ACT 1952-1969

COMPLETE SPECIFICATION (0ORIG INAL)

8.51 66/75 FOR OFFICE USE Class tnt. Class *4Aplcation Number: Lodged; p

.*omplete Specification-Lodged: coo Accepted: Published: and Au". utfPO uutste ~L~O104~

fl 4ated Art: 7 TO BE COMPLETED BY APPLICANT Name of Applicant. MOBIL OIL CORPORATION, a corporation organized and existing under the laws of the State of New York, of 150 East 42nd Street, New York, United Statos of America. **AqZress of Applicant:

Actual Inventor: ANTONYTHEORORE JUREWICZ and LEWIS BREWSTER YOUNG

Care of COWIE, THOMSON CARTER, Patent Attorneys of Address for Service: 343 Little Collins Street, Melbourne, Victoria, Australia.

Complete Specification for the invention entitled: REGENERATION OF VANADIUM-PHOSPHORUS CATALYST COMPLEX WITH ALKYL PHOSPHATES

fTme following statement is a full description of this invention, including the best method of performing it known to me:-*-1

*Notv: The description is to jbe typed in double s5pacing, pica type face, in an area not exceeding 9j-" in depth and 6V" in width, on tough white paper of good quality and it is to be inserted Inside this form.

1471717. -L I~fl1/,~ -L A.nctrisoN, Government Psinter, Canberra

TRAGROIJND OF THY, MNENTION

FIELD OF TgHE INVENTION

This invention is concerned with in situ regeneration of vanadium-phosphorus-oxygel catalyst complexes in the vapor phase oxidation of hydrocarbons to maleic anhydride.

:0::DESCRIPTION OF1 THE PRIOR ART 00 In United States Lrtters Patents Nos. 3,296,282 and -3.,474,041, thnre is described a method of rcgenerating

c vanadium-phosphorus-oxygen catalysts used In the oxidation of olefins (butene-2) to maleic anhydride. The method consists

of treating the catalys~t with phosphines, phosphites, or phosphonates by periodically or continuously passing

phosphorus compound to the reactor, with or without interrupting

00 olefin feed flow. The patentee does not teach that esters of orthophosphorir acid are effective and prefers phosphorus

.00 0 compounds wherein the phosphorus has a valence of less than

Un-*ted Statos 'Let~zes Patent No. 2,426,678 is

concerned with 1iV- regeneration of s'pent solid phosphate P0 dehydration catalysts withtl volatile trialkyl phosphates. The

patentee does not teach reqwrionrationi of vanad ium-phosphorus oxygen complex catalysts, whir.h are not phosphate catalysts. SUMMKARY OF THE INVENTION

Thi2 inventLion provides a mnethod for regenerating a promoted vanatliu -phnrus -roxygen vapor phase oxidation

catalyst, which 11-)mpis c onitacting said catalyst with an

ailkyl ester of orhpathr oc.1 having the formula

where in Bi s hydrogen or Cj-CL alkyl.

ESCRIPTIOi OF SPECIFIC EMBODIMENTS

The promoted catalysts that are regenerated

according to this invention are prepared by refluxing a

reaction mixture of vanadium oxide, phosphoric acid, a hydrogen

halide (usually hydrochloric acid), and a specified promoter

metal compound. In place of V 2 0 5 other vanadium compounds

such as VOC 3 VO(N0 3 3 NH4V03 and VF 5 can be used. Similarly,

O compounds hydrolyzable to phosphoric acid can be used, such t

S: as P205 and POC1.3 The hydrogen halides are HC1, HBr and O

HI. Alternatively, the promoter metal compound can be added

at a later stage of the catalyst preparation. For example,

the promoter metal compound can be added just prior to catalyst SS

pelletization. The proportions of reactants are selected to

afford an atomic ratio of phosphorus/vanadium of between

about 0.5 and about 2 and an atomic ratio of promoter metal/

vanadium of between about 0.0025 and about 1, preferably

between about 0.005 and about 0

The optimum atomic ratio of promoter metal/V will

depend upon the particular metal selected. In general, the

best ratio can be found from the specific working examples

of German Auslegeschrift No. 2328027, to which reference is

made, or can be readily determined with a minimum of experiments.

The reaction mixture is heated at reflux temperature

for between about 0.5 hour and about 24 hours, during which

time the solution changes color, usually from brown to dark

blue. Then, the reaction mixture is concentrated and evaporated

to dryness. The catalyst is prepared by grinding the resultant solid material to about 20-60 mesh size and pelletizing, for example, to 1/8" X 5/32" cylindrical pellets. Optionally, a binder,, such as stearic acid, can be added before pelletizing.

Alternatively, the reaction mixture or a concentrate thereof can be used to impregnate a suitable carrier, such as alumina or alundum, silica, silicon carbide, silica-alumina, zeolite, zirconium phosphate and/or zirconia, to produce a supported catalyst suitable for use in a fixed or fluidized bed reactor.

r As a further alternative, the dried catalyst (unsupported) can 00 be ground to produce a powdered catalyst for use in a fluidized 0@

bed reactor. S: In practice, the vanadium salt is added as vanadium oxychloride, which is formed by reaction in situ of vanadium pentoxide with hydrochloric acid. Alternatively, other oxyhalide salts of vanadium can be used, suitably prepared

•eby reacting vanadium pentoxide with another acid such as

hydrobromic or hydriodic. The phosphoric acid used generally will have a strength of between about 25 percent and about 100 percent. The promoter metal compound can be any compound IWO0 of the promoter metal, such as nitrate, chloride, acetate,

oxide, carbonate and 'the like. The promoter metals utilizable in the catalysts contemplated herein are chromium, iron, hafnium, zirconium, lanthanum and cerium. Iron and hafnium are particularly preferred for fixed bed operations, while zirconium is preferred for fluid bed operations. Zirconium generally provides a more active catalyst which provides higher yields of desired product maleic anhydride) at lower activity temperatures in fluid bed operations. The zirconium-promoted catalysts are generally harder, such that they have improved resistance to attrition as compared with the corresponding unpromoted catalyst, and with the corresponding catalysts promoted with other metals.

The charge stocks utilizable are alkanes having

between 4 and 10 carbon atoms, cycloalkanes having between

4 and 10 carbon atoms, or mixtures of hydrocarbons rich in

aelkanes and cycloalkanes having between 4 and 10 carbon atoms. e The alkanes can be normal alkanes or they can have slight

branching. Typical alkanes are butane, pentane, isopentane,

0 e1xane, isohexane, 3-methylpentane, heptane, octane, isooctane

and decane. The cycloalkanes utilizable can be methyl I

substituted and include cyclobutane, cyclopentane, methyl-

cyclopentane, cyclohexane, methylcyclohexane, 1,4-dimethyl-

cyclohexane, cycloheptane, and cyclooctano. Mixtures of

hydrocarbons rich in L _anes and cycloalkanes having between 4 and 10 carbon atoms, containing about 70 weight percent

or more alkanes and cycloalkanes, are well known in the art.

Particularly suitable and readily available mixtures are

09 naphthas obtained from paraffinic or naphthenic petroleum sources. Full boiling range naphthas (boiling within the

range of about 35-2300C) can be used but it is preferred to

use light naphtha cuts boilling within the range of about 1 5cC. Tuhe naphthas usually contain about 5-15 percent benzene and alkylbenzenes. It has been found that benzene

is oxidized to male te anhydride in the process of this

invention, whereas to some extent alkylbenzenes are oxidized

to benzene carboyli acids. It will be understood that other

mixtures can be used, such as paraffinic raffinate from the

glycol-water solvent extraction of reformates (Udex process).

BuLane, because of its ready availability, ai

preferred. In the following discussion and exemplification,

therefore, butane is used to demonstrate (but not to limit)

the present process for producing maleic anhydride and

catalyst regeneration. It is contemplated that mixtures

rich in butane can be used, such as a typical butane-butene refinery stream.

0 The oxidation of n-hutane (or other chargestock) to maleic anhydride is carried out using air or other -t

molecular oxygen-containing gases, such as mixtures of carbon

dioxide and oxygen or mixtures of nitrogen or steam with

air or oxygen. Air is preferred. The oxidation reaction is

carried out at temperatures of 300-600°C. Preferably, it is carried out at temperatures of 350-550 0 C. The feed 1 concentration will be 0.5-6 volume percent hydrocarbon charge

in the oxygen-containing gas and preferably 1-5 volume percent. The contact time will vary between about 0.08-3 seconds,

preferably about 0.16-1.6 seconds for fixed bed operation. Contact times of, for example, up to 30 seconds may be used in the case of a fluidized bed operation. Thus contact time,

depending upon the type of operation will be about 0.08-30

seconds. Although the reaction can be carried out at 0.5-20

atmospheres pressure (absolute), it is preferably carried out

at substantially atmospheric pressure, about 1-7 1 atmospheres press ure (absolute).

The reaction can be carried out in any suitable

reactor for effecting vapor phase oxidation reactions. Suitably;

a fixed catalyst bed can be employed. The reaction can be carried out, however, by using smaller catalyst particles in a fluidized reactor bed. In most of the following examples, except as noted, there was used a fixed-bed reactor consisting of 14" x 3/4" i.d. stainless steel tube equipped with a 1/4" o.d. axial thermowell for temperature measurement.

A 12" portion of the reactor was encased in a brass block.

Temperatures were measured at the hottest point in the

e catalyst bed and in the brass block. Heat was supplied to

S .the reactor through tubular electrical heaters. SQQ

3Q In the examples and tables of MA" indicates

6O maleic anhydride yield expressed as weight percent based upon the weight of butane feed and was determined by titration.

The flow rates of air and butane were measured at room

temperature and pressure. In the aforedescribed oxidation process, the

promoted vanadium-phosphorus-oxygen catalysts begin to lose

activity after a period of use. The yield of maleic anhydride

drops and, in some cases, the selectivity also drops. The

cetalyst can be regenerated or reverified by contacting it with an alkyl ester of orthophosphoric acid whil-* the oxidation

reaction is still in progress, without interrupting

the feed of hydrocarbon and oxygen.

The alkyl esters of orthophosphoric acid that are

utilizable are the mono-, di-, and trialkyl phosphates having

1-4 carbon atoms in the alkyl group. Non-limiting examples

include dimethy.l hydrogen phosphate, trimethyl phosphate,

ethyl dihydrogen phosphate, diethyl hydrogen phosphate,

triethyl phosphate, dipropyl h5 Irogen phosphate, triisopropyl phosphate, butyl dihydrogen phosphate, diisobutyl hydrogen phosphate, and tributyl phosphate. Trimethyl phosphate is preferred,

The phosphate ester can be added to the catalyst

by various methods, such as by addition in gaseous or liquid

form. The ester can be added by use of an aerosol or in

suspension in a carrier such as steam. The phosphate ester can be introduced via the oxygen feed or the hydrocarbon feed.

u' It has been found feasible to pass a portion of the oxygen 00 i (air) feed through a scrubber containing the phosphate ester 00

I 2 and then introducing the air into the reactor with the rest

of the air feed. The amount of phosphate ester can be controlled

by the length of time the air passes through the scrubber,

or by increasing or decreasing the rate of flow through the 0o

scrubber or even intermittently iiscontinuing the flow. The

Samount of alkyl ester of orthophosphoric acid added will be

between about 0.01 pound and about 0.2 pound per pound of

catalyst per year.

EXAMPLE 1 40 n-Butane was oxidized to maleic anhydride in a

one-inch, 4 foot long glass fluid bed reactor. The catalyst

was vanadium-phosphorus-zirconium catalyst (325 grams)

having an atomic ratio of 1/1.2/0.13. A 4% butane in

air mixture was passed through the catalyst at 4000C.

Under these conditions after 386 hours of continuous reaction,

the yield of maleic anhydride was 84.7% by weight at 92%

butane converison 5 4, selectivity). At the same conditions

after 985 hours of operation, the maleic anhydride yield

was 77.8% at 87.2% butane conversion (53% selectivity).

After 1200 hours of operation, a portion of the air stream of the total air stream) was passed through a scrubber containing trimethirl phosphate before entering the reactor as a saturated solution of trimethyl phosphate in air. During a ninete -n1-hour period, a total of 0.-Vg of tri'methyl phosphate was added. The yield of-maleic anhydride after 1320 hours was 83.3% at 81.8% butane conversion (60% selectivity). '-4 EXAMPLE II n-Butane was oxidized to maleic anhydride in a one-inch, 1 foot long steel. fixed bed reactor. The catalyst was a vanadium-phosphorus-iron catalyst having an atomic e. ratio of 1/1.2/0.03. A 2% butane in 1-1 air-stream was 0 passed through the catalyst at 4-i85 0 c. The initial yield (48 hours) of rnaleic anhydride was 67.6% by weight at 68% butane conversion (59% selectivity). After 168 hours the yield of maloic anhydride dropped to 37.2% at 82% 'butane conversiLon (27% selectivity). Trimethyl phosphate 3. 0 was added to the renctior by passin a. feed of trirothyl phoscphate In steam (0.759 trimethyl phosphate/liter of water) for one hour. A total 0.3L49 of trimethyl phosphate was added to the catalyst bed during this period. After lo thle .ours y-eld f Tpalelc -,nhydride was 64-. at 71% butane conversion (54% selectivity).

withpro 2.ed emlbolimont-17, it is to be understood that moifcais an d v 'i 4tis maj be resorted to, without

departing from the spirit an(I Kae of this invention, as those skilled in the art will readily understa Suchi modifications

and variations are considered to be ojitliin the pur< ad

All -9-

Claims (6)

Tne claims cetainng tne invention are as tollows:-

1. A process for the vapor phase oxidation of alkanes having

fron 4 to 10 carbon atoms, cycloalkanes having from 4 to

carbon atoms, or mixtures comprising alkanes or cycloalkanes

F having from 4 to 10 carbon atoms to form maleic anhydride, in

which the alkane, cycloalkane or mixture comprising the alkanes

r-4 or cycloalkanes is contacted with a vanadium-phosphorus-oxygen

QO catalyst complex promoted with zirconium, hafnium, chromium,

iron lanthanum, or cerium, the catalyst being regenerated by

contacting it during the vapor phase oxidation with an alkyl ester *0: of orthophosphoric acid having the formula (RO)3 P=0, wherein R

is hydrogen or C1 -C 4 alkyl.

2. A process according to claim 1 in which the alkyl ester is

trimethyl phosphate.

3. A process according to claim 1 or 2 in which the process

is continuous and amount of the alkyl ester used is from 0.01

to 0.2 pounds per pound of catalyst per year.

4. A process according to any of claims 1 to 3 in which the

alkane comprises n-butane.

5. A process according to claim 1 substantially as herein

described with reference to the examples.

6. Maleic anhydride produced by a process claimed in any of

claims 1 to

DATED this 5th Day of January, 1979.

MOBIL OIL CORPORATION.

COWIE, THOMSON CARTER PATENT TRADEMARK ATTORNEYS SUITE 5, 65 QUEENS ROAD IMELBOURNE, 3004, AUSTRALIA