CS238716B1 - A method for refining gases containing sulfur compounds - Google Patents

Abstract

The solution relates to a method of refining gases produced by gasification of carbonaceous raw materials with a mixture of oxygen and water vapor. It consists in an economically advantageous process of hydrolysis of carbonyl sulfide and selective hydrorefining and hydrogenolysis of unsaturated substances and heterocompounds in two stages and capture of decomposition components of metal carbonyls. Refining is carried out in two stages in the presence of catalysts containing Co-Mo as the active component on a mixture of hydrated bhmitic gel and alumina trihydrate promoted by potassium oxide and anhydrous alumina.

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for refining gases produced by gasifying carbonaceous feedstocks with a mixture of oxygen and water vapor after previously reducing the hydrogen sulfide content by scrubbing to below 1000 ppm and comprising an economically advantageous process for carbonyl sulfide hydrolysis metals as a result of their decomposition into a gaseous and non-volatile component that settles on the refining catalysts.

One of the processes of production of hydrogen and synthesis gases, which has been increasing in importance recently, is the oxygen-steam gasification of carbonaceous raw materials such as fuel oil, heavy petroleum residues, coal, etc. Gasification generates the so-called desulphurized synthesis gas. contained in H ^S, COS, HCN, NHj (CN Fe) and inorganic elements predominantly in the form of the carbonyl groups Fe and Ni, all of which are for most of the subsequent catalytic processes of producing technical hydrogen and synthesis gas catalytic poisons such as sulfur compounds, or clog the surface of catalysts, such as metal carbonyl decomposition products, thereby reducing catalyst activity, such as ferrochromium conversion catalysts, or completely deactivating catalysts with only trace poisons, such as copper CO conversion catalysts, and Ni catalysts methanation. Therefore, even in the case of the use of sulfur-resistant conversion catalysts, all pollutants must be scrubbed at a certain stage in the production process. The COS scrubber is considerably more demanding than the acid gas scrubber and therefore the COS is removed by hydrolysis to H 2 S and CO 2. For this reaction to occur, the gas entering the refining reaction is saturated with water vapor to a content of 3-5% by volume.

In proportion to the water vapor content of the gas, the activity of the hydrogenation catalysts at operating temperatures of 140-180 ° C is suppressed. Hydrolysis is still operationally carried out in two stages, namely at kobaltomolybdenovém catalyst on alumina in the first step (approximately 5 m ^ catalyst), and on alumina in the second step (30 m ^ catalyst) after pre-reduction of hydrogen sulfide _- of thanks for the first scrubbing step to a content of the order of 10% by volume of sulfur compounds (COS and HgS). A more energy-efficient hydrolysis process on a combination of the same or similar catalyst without

Pre-wash stage 1 and at volumetric velocities above 5,000 h ”at high hydrogen sulphide and CO 2 content and low water vapor content and at low temperatures in both reactors cannot reliably reduce the COS content of the gas to the required limit due to reaction kinetics and thermodynamics below 10 ppm COS. Thus, in the first stage of refining, cobaltomolybdenum catalysts on alumina, the so-called comexes, which contain 0.5 to 4.6 wt. %, 8 to 15 wt. lioOj on alumina. Under their operating conditions, their activity is also suitable for the removal of oxygen from the gas. Complete hydrolysis of COS is achieved in step 2 on alumina. These facts were. It has been found that other economically advantageous catalysts can be used for the given reactions and reaction conditions. It has been found that the hydrolysis of heterocompounds, hydrogenation of oxygen, if present in the gas, and the decomposition of carbonyl are practically performed on the coex catalyst only if their content exceeds the thermodynamic conditions. The desulphurized synthesis gas practically does not contain any other compounds which would have to be removed by hydrorefination prior to the conversion of CO by water, by steam, although this fact makes it possible to utilize the gas for refining before the gas is converted in the first stage and possibly in the second stage of hydrolysis. COS and catalysts with lower hydrotreating activity, but with higher or the same hydrolysis activity. Therefore, mainly catalysts and alumina discarded after use in other processes and more affordable catalysts and recently also active alumina prepared based on a mixture of alumina hydrates by annealing above 300 ° C were tested. Mainly the hydrolysis activity or decomposition of metal carbonyl, which degrades every catalyst by decomposition products, was also monitored, which also forces the use of cheaper catalysts with satisfactory activity.

Process for refining gases with sulfur compounds below 1000 ppm vol produced by gasification of carbonaceous feedstocks with a mixture of oxygen and water fumes for the production of hydrogen and synthesis gases by hydrolysis of carbonyl sulfide, hydrotreating and hydrogenolysis of unsaturated substances and heterocompounds and capture of decomposition products

2387) 6 the presence of catalysts containing oxides and / or metal sulfides of Groups 6, 8 and 1 of the Periodic Table of the Elements on a mixed carrier of hydrated alumina in combination with aluminum oxide alone, at a temperature of 150 to 200 ° C, pressure 0.1 to 8, preferably >

Up to 5 MPa, a water vapor content above 0.005 kg HgO / nr gas and a catalyst volume loading of 1,000 to 30,000 gas volumes per hour per catalyst volume, according to the invention, consists in refining to Co-Mo or Ni in stage I - To a catalyst containing 1 to 1 wt. % cobalt or nickel, 6 to 15 wt. % molybdenum, automated from 0.2 to 10 wt. potassium oxide on a mixed carrier consisting of hydrated bhmitic gel and aluminum oxide trihydrate in a ratio of 1 to 10: 9 or / and oxidatively regenerated hydrotreating Co-Mo and / or Ni-Mo catalyst and / or on alumogel and in the second stage anhydrous alumina, optionally pre-used as a sorbent for drying gas or alumogel.

Thus, an alkalized cobalt molybdenum catalyst with a lower content of expensive active ingredients and a higher conversion activity and in particular an oxidatively regenerated process cobalt molybdenum catalyst used for hydrotreating petroleum feedstocks with intermediate products satisfies the refining conditions: different types of alumogels, alumina, and optionally alumogel sorbents used for drying gases. The filling volumes of the individual refining stages can be reduced. Examples 1 and 2 show the results of laboratory and operational monitoring of the properties of selected 3-6 catalysts more economically advantageous than catalysts 1 and 2 used hitherto.

Example 1

Description of laboratory tested catalysts

1. A spherical alumogel-standard hydrolytic catalyst, virtually pure anhydrous alumina.

2. The Co-Mo / Al2 O4 catalyst contains, in addition to the anhydrous Al2 O4, also cobalt Co and 13% Mo molybdenum.

3. Co-Mo / AlgO-j catalyst containing 2.5 wt. Co, 9% Mo, promoted by 8% potassium to KgO and containing ΑΙ, Ο ^ in the form of a hydrated bis-gel and trihydrate in a ratio of about 1: 1.

4. A mixture of hydrated bhhmitic gel and alumina trihydrate in a weight ratio of about 1: 1, shaped into rollers after peptization with 2% K ₂ CO 4,

5. The cobalt molybdenum catalyst used for hydrotreating petroleum feedstocks containing, in addition to the elements listed in Catalyst No 2, 4% of sulfur in the form of sulphides.

6. Practically pure alumina used for gas drying.

The results of the laboratory measurement of catalyst activity expressed as a percentage of catalyst 1 activity are shown below.

Cat.

temperature ° C 1 2 3 4 5 6 160 , 00 64 & b 103 80 102 180 , 00 97 97 100 ALIGN! 90 100 ALIGN! 200 100 ALIGN! 99,5 100 100 ALIGN! 95 100 ALIGN!

Catalyst No. 1 based on pure alumina was taken as a standard because it is operationally used as one of the most active hydrolysis catalysts. If it is not necessary to remove traces of oxygen that may be present in the gas, only alumina-based catalysts are used. The oxygen removal is transferred to a catalytic conversion process

Carbon monoxide CO by steam.

Example 2

Performance test of the combined load

Based on the laboratory results and taking into account the economics of the refining process, a combined catalyst bed 3 and 5 and its properties were compared to the standard in-line catalyst bed operating in the current manner for the operational test. The filling according to the invention is cheaper compared to the standard filling and, moreover, the imported raw materials are saved. The first stage of refining is followed by stage 2, where the stage 1 and stage 2 reactors are connected in series and run under virtually the same conditions.

Composition of the gas entering the 1st stage of refining

component mol. % C0 ₂ 4.2 WHAT 45.8 «2 48.7 inerty 1.3 HgS 250 ppmv WHAT WITH 300 ppmv Fe and Ni carbonyls 2 to 5 mg of metals / m 2 water vapor content 0.01 kg in m @ 2 of gas pressure 3.2 MPa temperature (inlet) 150 [deg.] C vol 20 300 v / v h Reactor catalyst charges 1 . degree of gas refining: the current way the method of the invention 5 m ^ of catalyst (No. 2) 1.5 Catalyst (No. 3) 5 x 5 mm tablets extrudes έ 6 mm filled in the reactor outlet part 2.0 nP oxidative regenerated cobalt molybdenum hydrotreatment catalyst No. 5 the remaining volume is filled with ceramic rings Reactor catalyst charge 2. degree of gas refining: the current way the method of the invention 30 m ^ of catalyst (No. 1) 30 m ^ of catalyst (No. 1)

Process properties of catalyst packings after 1000 hours of operation

1st stage 2nd stage current method according to the current method according to the invention method of the invention content of COS output ppm 200

230 HgS content output ppm 350

340

430

525 carbonyls mg metals / m ³ 0.6 to 2 0.6 to 2 ^{* 4}

0.6 to 2

0.6 to 2

In accordance with the laboratory results, the operating experiment confirms the high hydrolysis activity of the alumina catalyst in the second stage of refining, which makes it possible to use catalysts with relatively lower hydrolysis activity in the first stage.

Claims (1)

SUBJECT OF THE INVENTION Process for refining gases with sulfur compounds below 1000 ppm by volume, produced by gasification of carbonaceous feedstocks with a mixture of oxygen and steam for the production of hydrogen and synthesis gases, hydrolysis of carbonyl sulphide, hydrotreating and hydrogenalysis of unsaturated substances and hetero compounds in the presence of catalysts containing oxides and / or sulphides and / or metal salts of Groups 6, 8 and 1 of the Periodic Table of the elements on a mixed carrier of hydrated alumina in combination with aluminum oxide alone, at a temperature of 150 to 200 ° C, pressure 0 1 to 8, preferably 2 to 5 MPa, a water vapor content in excess of 0.005 kg H ₂ O / m ^{3 of} gas and at a catalyst volume loading of 1000 to 30,000 gas volumes per hour, not catalyst volume, characterized in that in 1. In the step, refining is carried out on a Co-Mo or Ni-Mo catalyst containing 1 áž 4 wt. % cobalt or nickel, 6 to 15 wt. % molybdenum promoted 0.2 to 10 wt. potassium oxide, on a mixed carrier consisting of hydrated bhmitic gel and aluminum oxide trihydrate in a ratio of 1 to 0: 9 or / and on an oxidatively regenerated hydrotreating Co-Mo and / or Ni-Mo catalyst and / or on an alumogel and anhydrous alumina, optionally pre-used as a sorbent for gas drying and / or on alumogel.