US2646388A

US2646388A - Hydrodesulfurization process

Info

Publication number: US2646388A
Application number: US222150A
Authority: US
Inventors: Vincent L Crawford
Original assignee: Gulf Research and Development Co
Current assignee: Gulf Research and Development Co
Priority date: 1951-04-20
Filing date: 1951-04-20
Publication date: 1953-07-21
Anticipated expiration: 1970-07-21

Description

Patented July 21,1953 r UNITED STATES PATENT, OFFICE" t 9 2,646,388 a V A HYDRODESULFURIZATION PROCESS Vincent L. Crawford, Fox Chapel, Pa., assignor V to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application Aprilzo, 1951,

1 Serial No. 222,150

This invention relates toimprovements in the 'desulfurization of hydrocarbons rutilizing a I nickel-containing desulfurization contact or catalytic agent.

Contact and catalytic agents containing free or reduced nickel may be used for desulfurizing petroleum oil either by absorbingsulfur from the oil through the formation of sulfur compounds of nickel, or by catalyzing the conversion of the sulfur in the oil into hydrogen sulfide which is washed from the product.- See for instance Cornell application Serial No. 92,436, filed May 10, 1949, now U. S. Patent 2,614,066, McAfee ap-' plication Serial No. 63,157, filed December 2, 1948,

now abandoned, and us. Patents 2,070,295,-

2,298,347, and 2,406,200 which refer to the 'employment of 'metallic nickel as a desulfurization contact or catalyst.

In such usagethe nickel progressively loses desulfurizing activity because of contamination by sulfur and/or carbonaceous-'1;

materials. It is therefore necessary periodically to regenerate and reactivate the nickeliferous agent by oxidizing to remove sulfur and carbonaceous contaminants and by then reducing with hydrogen gas to reconvert a substantial portion of the nickel therein'to the free metallic state.

This reduction is an exothermic reaction and y the contact is not at the proper temperature for the on-stream phase of the desulfurization process and must be either heated or cooled with resulting expense and time loss to attain the required temperature for continuation of the desulfurization process. I

' This invention has 'for an object to provide 'tion ofa nickel salt such as nickel nitrate, drya method for desulfurizing hydrocarbons where'- in the temperature is controlled during thereactivation of an oxidized 'nickeliferous contact or catalyst.

A further object is to provide a method for desulfurizing hydrocarbons in which the nickeliferous contact or catalytic agent used in the process is reactivated by a controlled reduction whereby damage to the agent due to excessive temperature during reduction is avoided.

A still further object is to provide a process for desulfurizing hydrocarbons inwhich the nickeliferous contact or catalytic agent used in the process is reactivated by a controlled reduction, whereby the pressure of the system and the temperature of the agent at the end of the reduction are substantially equal to the pressure and temperature required for the on-stream 4 Claims. (01. 196- 28) These and other objects are accomplished by the following invention in which a sulfur containing hydrocarbon in vapor phase is desulfurized by contacting it at elevated pressure and ata temperature between about 820 and 875F. with hydrogen and a nickeliferous agent comprising between about 15 and 25 per cent nickel calculated as oxide deposited on a porous support,a substantial portion of said nickel being in the metallic form, terminating the contact of vapor, hydrogen, and nickeliferou's agent when regeneration is required, depressuring, regenerating the nickeliferous agent by combustion, at least partially reducing the regenerated nickeliferous agent by treating said agent at an initial reduction temperature between about Z50 and 800 F. and at a pressure approximately equal to the reaction-pressure with a mixture of steam and reducing gas, the mol ratio of'stea'r n to re- -ducing gas being between about 4.511 and 28:1 and being such as to give said agent'a final temperature after reduction atleast about 40 F.

higher than the initial reduction temperature but between about 820 and 875 F., terminating the flow of steam and immediately contacting vapors of the sulfur containing hydrocarbon with hydrogen and the regenerated and at least partially-reduced nickeliferous agent while still at approximately said final. temperature and reaction pressure.

The nickeliferous agent herein referred to includes the sulfur absorbent contact type which desulfurizes'by combining with sulfur in the oil;

the catalytic type which catalyzes conversion of sulfur in the oil into hydrogen sulfide which may belwashed from the product; and the type which initially in the process is sulfur absorbent but becomes catalytic after being sulfurized in the course of the desulfurization process. These 'n'ickeliferous' agents may be prepared by impregnating a porous's'upport material with a soluing. and calcining to form nickel oxide on the support, and at least partially reducing the oxidized mass bytreatment with a reducing gas at elevated'temp'erature. v'lhe'agents suitable for use in my process contain between about 15 and 25 per cent by weight nickel calculated asoxide based on the total weight of thesupport and agent. form of free metallic nickel, nickel oxide, nickel sulfate, or nickel sulfide but will contain at least a substantial amount of free nickel at the beginning of the desulfurization process. Among the suitable porous support materials are, alumina, kieselguhr, silica gel, aluminum silicates, bauxite, Alfrax; Magnesol, Porocel, or silicaalumina carriers, especially of the cracking catalyst type whether active or inactive for cracking.

My process may be employedto desulfurize.

The agents may contain nickel in the various sulfur-containing hydrocarbons such as gasoline, naphtha, gas oil etc. but is particularly adapted for desulfurizing sulfur-containing heavy deposited on a porous support under the following preferred conditions: temperature between about 820 and 875 F., pressure between about 300 and 1000 p. s. i.; liquid hourly space velocity of the oil, between about 0.2 and 6.0 volumes of oil per volume of nickeliferous agent; hydrogen concentration between about 1000 and 10,000 or more cubic feet per barrel of oil. During this processv sulfur is removed from the oil either by combining with the nickel in the agent or by forming hydrogen sulfide which is removed from the product by caustic washing or other suitable method. In either case, the nickeliferous agent progressively loses its desulfurizing activity during the process because of the formation of sulfur and/or carbonaceous contaminants on the agent.

When the deposition of the contaminants has seriously lowered the desulfurizing activity of the nickeliferous agent, the contacting with oil vapors isterminated, the system is depressured and the agent is regenerated by contacting with an oxygen-containing regeneration gas at an elevated temperature to burn off carbonaceous deposits and at least partially remove sulfur combined with nickel thus forming nickel oxide. Following the regeneration theagent is reactivated by treatment with a reducing gas at approximately the pressure desired in the reaction phase or onstream' phase to reconvert a substantial portion of the nickel to the metallic state. This reduction reactivation must be initiated at a temperature between 750 and 800 F. If an initial temperature below about 750 F. is used the reduction does not proceed satisfactorily and if a temperature above about 800 F. is used initially it is very difficult and uneconomical to restrict the final temperature to the desired cn-stream temperature. I therefore control the temperature of the preceding oxidation treatment so that the nickeliferous agent at the end of the oxidationtreatment will be at the proper temperature for initiating the reduction reactivation. Such control of the regeneration temperature may be accomplished by regulating the amount of oxygen in the regeneration gas and/or the temperature of the diluent gas which is usually steam.

Durin regeneration by oxidation of a body of catalytic or contact material of the type employed in my process, a burning Zone progresses through the body of material from one end to the other. Unless steps are taken to avoid it, in the final stages of the regeneration the first oxidized portion of the material will have cooled and will be at a lower temperature than the subsequently oxidized portions. This may be avoided and a uniform temperature throughout the catalytic or contact material may be obtained by preheating the regeneration gas to a suitable temperature (e. g. between about 750 and- 800 F.) to give the desired initial temperature for reduction throughout the body of regenerated material.

Immediately prior, to the reduction phase of my process the nickeliferous agent is in the oxidized state, at a temperature between about 750 and 800 F., and comprises a complex mixture of nickel oxide and a porous support material plus nickel sulfate, small amounts of nickel sulfide and carbonaceous materials, and perhaps other impurities. It should be emphasized the invention is unique to nickeliferous contact agents of the type described which are employed in a desulfurization process and further, to such contacts which are regenerated by combustion. This is because the unusual nature of the contact causes it to behave in a unique manner as compared with normally analogous metallic oxides.

The reduction reaction of this complex mixture with hydrogen or other reducing gases is highly exothermic. Therefore, if the reduction is effected with no temperature control, an excess'ive temperature rise will occur in the. agent which will. cause sintering of the nickel or disintegration of, the porous support, or both, and at the end of the reduction treatment the temperature. will be so high as to require COOllllg of the agent before introducing sulfur-containing oil for the ensuing desulfurization cycle.

To allow the final temperature of the bed to exceed the'maximum allowable limit of about 875 F. is disadvantageous not only because of the danger of damaging the nickeliferous agent and/or the support but because of the high coke and gas production and rapid deactivation of the contact agent at temperatures exceeding this limit during the subsequent processing period or on-streamphase. To attempt to avoid the latter diinculty by cooling the reduced nickel agent after themaximum temperature has been exceeded is entirely unsatisfactory, since this involves depressuring, flushing with, for example, steam and repressuring with. hydrogen. Under this procedure the length of the off-stream period (non-productive time) is increased substantially, substantial quantities of hydrogen are wasted, a more complex control is necessary, and the risk of deactivating the agent and/or support with the cooling gas is created.

In view of the factsv discussed above, it will be obvious that an esesntial feature of my invention is the control of the initial temperature at which the reduction is started and control of the temperature during reduction utilizing certain amounts of steam mixed with hydrogen to produce a reduction final temperature of the nickeliferous agentbetween abouti820 and 875 This temperature range is suitable for the de sulfurization phase of the process, and thus the contacting of the sulfur-containing hydrocarbon vapors with the regenerated and reactivated nickeliferous agent may be resumed while the agent is still at approximately its final reduction temperature.

As an illustration of my invention, the following example shows a typical operating cycle with conditions for the on-strearn period, the regen- 1 eration period and the reduction period.

EXAMPLE The catalyst used was prepared by impregnation of dried 6-10 mesh silica gel with an aqueous nickel nitrate solution followed by drying at 250 F. and subsequent calcining at 800 F. to convert the nickel nitrate to nickel oxide.

This sequence. of. impregnation, drying and calcining was repeated twice, so that the final catalyst contained 18 per cent nickel oxide and 82 per centv silica gel. ,The catalyst was then partially reduced by treatingat 800 F. with hydro- Distillation, Percent at:

Liquid Recovery Vol. Percent; .Dry Gas, cu. ft./B

genand steam. The catalyst was then ready'for the reaction period. After a reaction period the reactor was depressured, and the catalyst was regenerated by combustion. At the end of the regeneration period, in which the final temperaterminated and oil out into the reactor for a processing period. The conditions for the "-regeneration, reduction, and processing periods are given in the table below.

V Table 1 Regeneration step:

Pressure, p. s. i. g. Q. 1 100 Reactor Temperature, F.

' Outlet 1150 Steam rate, lbs/lb. oxidized catalyst 13 Air rate, SCF/lb. oxidized catalyst 29 Time, min. 120 Reduction step: v

Pressure, p. s. i. g 500 Reactor temperature, F.-'

Average 825 Maximum 850 Steam rate, lbs/lb. oxidized catalyst"; 1.50 Hz rate, SCF/lb. oxidized catalyst' 1.20 Steam-hydrogen mol ratio 26.421 Reduction time, min. 15'

Operating step: Y I

Temperature, F 850 Pressure, p. s. i. g. 1 500 Space velocity, vol./vol 1 Throughout, vol/vol. Cat 4 H2 circulation, CF/bbl 2000 Product data are shown in Table 2 immediately below:

' Table 2 Charge and .Production Inspection:

Charge (Kuwait Crude) Product Carbon Midi 5'66 Carbon. Wt. Percent of Charge.

The data -presented in Table 1 illustrate an operative example of the desulfurization process utilizing the feature of controlled'reduction' of a supported nickeliferous' agent containing -25, per cent nickel calculated as oxide. The data of Table 2 illustrate the benefits obtained by this process, i. e., high degree of upgrading, high de not occur, while above the maximum of about 7 875 Ethe rate of desulfurization doesnotma terially improve and a larger, more rapid decomreducing gas with steam.

. 6 position of the oil to carbon and gas is encountered. Thus in reducing the nickeliferous agent by my process I raise the temperature of the agent from its initial temperature of between about 750 and'800 F. to at least about 820 F..

and I avoid a final reduction temperature of the agent higher than about 875 F., by diluting the The amount of steam required varies with the temperature rise to be obtained and .the initial temperature, a relatively large amount of steam being required to limit the temperature rise to a small value. and a relatively smaller amount of steam being required for a greater rise in temperature. The largest possible temperature rise'that would be permittd. in my process is from 750 F. to 875 F. or a'rise of F. vI have discovered that this particular temperature rise of 125 F. can be obtained by employingin the reduction a steam-hydrogen ratio of 4.5 mols of steam per mol of hydrogen. To limit the temperature rise to less than 125 F. a larger amount of steamiin the steam hydrogen mixture isrequired. For example, I have found that a ratio of 28 mols of steam per'mol of hydrogen is re quired to limit the temperature to a 40 F. rise. To limit the temperature rise to any smaller value than 40 F. requires much larger and uneconomical amounts of steam. For example 166 mols of steam per mol of hydrogen is-required to limit the temperature rise to 20 F.

Since such large amounts of steam are re-; quired ,to limit the temperature rise to less than 40 F., it is undesirable to operate at a temperature differential of less than 40 F. both from'the 'standpoint of steam economy and the possibility of poor hydrogen efficiencyif the reduction gas is too dilute. f Thus, my invention involves the use of a steam-hydrogenratio which will produce a temperature rise intermediate between 40. and

125 F. is required, a steam-hydrogen mol ratio proportionately intermediate between 28:1 and 4.521 is employed.

Since 'it'is desirable to maintain a uniform catalyst bed temperature during the reduction step, the'reduction gases may be preheated so that the inlet temperature of these gases approaches' the desired initial temperature for th reaction step. e

Thus, after regenerating the nickeliferous agent by oxidation under conditions which give a temperature or 750 to 800 F. for the oxidized agent, Iselect'the proper steam-hydrogen ratio -.which will raise-the agent temperature during reduction at least 40 F. .from a point between about750 and 800 F. to a desired point between about "820 and 875 F. "The agent is then conwithout the necessity of first heating or cooling hydrogenfrom the desulfurization process gases absorbed in the desulfurized product and removed therefromduring subsequent fractionation may be used. Also low molecular weight hydrocarbons such as methane and ethane alone 'or-inadmixture with other hydrocarbons or .hy-

drogen may be employed.

\Vhat I claim is:

lpThe process for sulfurizing a hydrocarbon which comprises contacting vapors of a sulfurcontaining'hydrocarbon at elevated pressure and at a temperature between about 820 and 875 F.-with hydrogen and a 'nickeliferous agent comprising between about and per cent nickel calculated as oxide deposited upon a porous support, .a substantial portion of said nickel being in the .metallic form, terminating contact between the vapors, hydrogen, and .nickeliferous agent when regeneration is required, depressurizing, regenerating the nickeliferous agent by combustion, at least partially reducing the regenerated nickeliferous agent by'treating said agent at an initial reduction temperature between about 750 and 808 F. and at a pressure approximately equal to the reactionpressure with steam and simultaneously treating said agent with a reducing gas, the mol ratio of steam to reducing gas being between about :1 and 28:1 and being such as to give said agent a final temperature after reduction at least about 48 F. higher than the initial reduction temperature but between about 820 and 375 F., terminating the flow of steam and immediately contacting vapors of the sulfur-containing hydrocarbon with hydrogen and the regenerated and at least partially reduced nickeliferous agent while still at approximately said final temperature and reaction pressure. i. g

2. The process'for desulfurizing a hydrocarbon which comprises contacting vapors of asulfurcontaininghydrocarbon at elevated pressure and at a temperature between about 1820" and875 F. with hydrogen and a nickeliferous contact agent comprising between about 15 and 25 per cent nickel calculated as oxide deposited upon a porous support, a substantial portion of, said nickel being in the metallic form, terminating contact between the vapors, hydrogen, and nickeliferous contact agent when regeneration is required-depressuring, regenerating the nickeliferous con- 1 tact'agent by combustion .in the presence of ,an oxygen-containing gas, controlling. the regeneration to give said agent a temperature after regeneration ofbetween about 750 and 800-F.,

at least partially reducing therregeneratednick- I eliferous contact agent by treating said agent at approximately reaction pressure and while at about this temperature with steam and simultaneously treating said agent with hydrogen, the molratio of steam to hydrogen being between about 4.5:1 and 28:1 and being such as to give said agent a final temperature after reduction at least about 40 F. higher than the temperature at the beginning of the reduction treatment but between about 820 and 875 F., terminating the flow of steam and immediatelycontacting vapors, of the sulfur-containing hydrocarbon with hydrogen and the regenerated and at least partially reduced nickeliferous contact agent while still at approximately said final temperature and reaction pressure.

3. The process for desulfurizing heavy hydrocarbons which comprises contacting vapors of a sulfur-containing heavy petroleum oil at elevated 8 pressure and at a temperature between about 820 and 875 F. with hydrogen and a nickeliferous contact agent comprising between about 15 and 25 per cent nickel calculated as oxide deposited upon a porous support, a substantial portion of said nickel being in the metallic form, terminating contact between the vapors, hydrogen, and nickeliferous contact agent when regeneration is required, depressuring, regener ating the nickeliferous contact agent by combustion in th presence of an oxygen-containing gas, controlling the regenerationto give said agent a temperature after regeneration of between about 750 and 800-F., at least partially reducing the regenerated nickeliferous contact agent by treating said agent at approximately reaction pressure and while at about this temperature with steam and simultaneously treating said agent with hydrogen, the mol ratio of steam to hydrogen being between about 4.5:1 and 28:1 and being such as to give said agent a final temperature after reduction at least about 40 F. higher than the temperature at the beginning of the reduction treatment but between about 820 and 875 F., terminating the flow of steam and immediately contacting vapors of the sulfur-containing heavy petroleum oil with hydrogen and the regenerated and at least partially reduced nickeliferous contact agent while still at approximately said final temperature and reaction pressure.

4. The process for desulfurizing a hydrocarbon oil which comprises contacting vapors of a sulfur-containing hydrocarbon oil from the group consisting of total crude, topped crude, and reduced crude at elevated pressure and at a temperature between about 820- and 875 F. with hydrogen and a nickeliferous contact agent comprising between about 15 and 25 per cent nickel calculated as oxide deposited upon a porous support, a substantial portion of said nickel being in the metallic form, terminating contact between the vapors, hydrogen, and nickeliferous contact agent when regeneration is required, depressuring, regenerating the nickeliferous contact agent by combustion in the presence of an oxygencontaining gas, controlling the regeneration to give said agent a temperature after regeneration of between about 750 and 800 at least partially reducing the regenerated nickeliferous contact agent by treating said agent at approximately reaction pressure and while at about this temperature with steam and simultaneously treating said agent with hydrocarbon, the mol ratio of steam to hydrogen being between about 4.5:1 and 28:1 and being such as to give said agent a final temperature after reduction at least about 40 F. higher than the temperature at the beginning of the reduction treatment but between about82fl" and 875 F.,terminating the flower" steam and'irnmediately contacting vapors of. the sulfur-containing hydrocarbon oil with hydrogen and the regenerated and at least partially reduced nickeliferous contact agent while still at approximatelysaid final temperature and reaction pressure.

" VINCENT L. CRAWFORD.

References Cited in the file of this patent 2,560,433 Gilbert et a1 July 1-0, 1951

Claims

1. THE PROCESS FOR SULFURIZING A HYDROCARBON WHICH COMPRISES CONTACTING VAPORS OF A SULFURCONTAINING HYDROCARBON AT ELEVATED PRESSURE AND AT A TEMPERATURE BETWEEN ABOUT 820* AND 875* F. WITH HYDROGEN AND A NICKELIFEROUS AGENT COMPRISING BETWEEN ABOUT 15 AND 25 PER CENT NICKEL CALCULATED AS OXIDE DEPOSITED UPON A POROUS SUPPORT, A SUBSTANTIAL PORTION OF SAID NICKEL BEING IN THE METALLIC FORM, TERMINATING CONTACT BETWEEN THE VAPORS, HYDROGEN, AND NICKELIFEROUS AGENT WHEN REGENERATION IS REQUIRED, DEPRESSURIZING; REGENERATING THE NICKELIFEROUS AGENT BY COMBUSTION, AT LEAST PARTIALLY REDUCING THE REGENERATED NICKELIFEROUS AGENT BY TREATING SAID AGENT AT AN INITIAL REDUCTION TEMPERATURE BETWEEN ABOUT 750* AND 800* F. AND AT A PRESSURE APPROXIMATELY EQUAL TO THE REACTION PRESSURE WITH STEAM AND SIMULTANEOUSLY TREATING SAID AGENT WITH A REDUCING GAS, THE MOL RATIO OF STEAM TO REDUCING GAS BEING BETWEEN ABOUT 4.5:1 AND 28:1 AND BEING SUCH AS TO GIVE SAID AGENT A FINAL TEMPERATURE AFTER REDUCTION AT LEAST ABOUT 40* F. HIGHER THAN THE INITIAL REDUCTION TEMPERATURE BUT BETWEEN ABOUT 820* AND 875* F., TERMINATING THE FLOW OF STEAM AND IMMEDIATELY CONTACTING VAPORS OF THE SULFUR-CONTAINING HYDROCARBON WITH HYDROGEN AND THE REGENERATED AND AT LEAST PARTIALLY REDUCED NICKELFEROUS AGENT WHILE STILL AT APPROXIMATELY SAID FINAL TEMPERATURE AND REACTION PRESSURE.