CS222807B1 - Method of removing the oxyganic compounds of the carbon from technical hydrogen - Google Patents

Description

The invention relates to a process for the removal of oxygen compounds from industrial hydrogen by methanation on nickel catalysts optionally modified with precious metals of Group 8, in which the reaction is carried out on nickel catalysts of different active ingredient content which is first reduced in the reactor. The use of a catalyst with a high content of active ingredient in the catalyst bed inlet bed makes it possible to reduce the methanation inlet temperature to 110 to 270 ° C, thereby achieving energy savings.

At the same time, the process makes it possible to monitor the course of catalyst deactivation by means of temperatures in the methanation reactor.

The invention relates to an improved process for the removal of oxygenated carbon compounds from industrial hydrogen by hydrogenating them to methane on nickel supported catalysts or supported catalysts containing precious metals of Group 8 of the Periodic Table of the Elements.

One of the most widely used processes for producing hydrogen is by converting carbon monoxide with water vapor followed by CO2 scrubbing and converting residual carbon oxides by hydrogenation to hydrogen on nickel supported catalysts or supported catalysts containing Group 8 precious metals, in particular rutenium. It is not decisive what material and process gas was produced. Recently, catalysts having an NIO content of 15 to 25% by weight or 0.2 to 5% by weight have been used. of precious metals on carriers. Industrial gases contain numerous trace poisons, such as sulfur and chlorine, which reduce the activity of all types of catalysts used hitherto. Iron and nickel carbonyls also reduce the activity of the catalyst, particularly low-concentration catalysts containing precious metals. Therefore, the use of these catalysts at temperatures below 250 ° C becomes problematic in terms of cost and durability. In the case of nickel catalysts, activity increases with increasing nickel content, but at the same time increases in proportion to nickel content, yet they are cheaper and more affordable than catalysts containing precious metals.

According to the present invention, a novel process for removing oxygen-containing carbon compounds from industrial hydrogen has been found by hydrogenating them to methane on nickel supported catalysts or supported catalysts containing precious metals of Group 8, which are fed into the reaction space in oxidic or pre-reduced form. characterized in that the technical hydrogen is placed on a catalyst layer consisting of at least two types of catalyst with different active nickel content or modified noble metals of the 8th group of the periodic system which are reduced by hydrogen or technical hydrogen at temperatures gradually before the methanation reduction rising to 300 to 350 ° C at a pressure of 0.1 to 10 MPa and at a reducing gas volume rate of 250 to 3000 v / v. h for at least 12 hours, for a pre-reduced catalyst of at least 4 hours, after which the temperature of the catalyst bed is gradually reduced to 130 to 270 ^° C, preferably 210 to 250 ° C, at which methanation purification of technical hydrogen begins to 5 ppm oxygen in the gas exiting the catalyst bed, at a volumetric rate of 5,000 to 10,000 v / v. of catalyst per hour, monitoring the aging and poisoning of the catalyst bed by measuring the temperature profile in the bed and reaching 9,000 to 12,000 v / v. of active catalyst, the reaction is stopped and part of the deactivated catalyst is replaced with active.

The catalyst bed feed layer comprises a catalyst with the highest nickel content, preferably 30 to 50 wt. % NiO and the catalyst exit layer having the lowest nickel content, preferably 10 to 25 wt. NiO and / or catalyst partially deactivated in the previous operating cycle.

In the treatment of industrial gases using catalysts with a NiO content above 30% by weight. it is advantageous to purify the technical hydrogen at a starting temperature of 200 to 260 ° C, thus achieving a significant reduction in energy consumption in lines equipped with a gas preheater at the inlet of the methanation reactor and still operating at a starting temperature of 280 to 300 ⁹ C. With a higher Ni content, it is advantageous to charge the reactor with two or more kinds of Ni catalysts, optionally in combination with precious metal activated catalysts.

When using only Ni-catalysts with different Ni contents, the reactor is preferably charged such that the Ni content of the catalyst used for the filling decreases in the direction of gas flow. In case the gas does not contain base metal carbonyls or other volatile compounds thereof and other poisons, it may be advantageous to fill the reactor inlet layer with a low-temperature, precious-metal activated catalyst.

A major problem in determining the practical lifetime of the catalyst charge of a methanation reactor using different Ni catalysts and determining the appropriate time interval for partial catalyst replacement is to determine the degree and rate of catalyst deactivation by both aging and poisoning contained in industrial gas. characterized by a rapid rise in the temperature of the catalyst bed to a temperature given by the gas inlet temperature, the oxygen content of the gas present, and the desired end conditions, i.e. the CO and CO2 content. The interface between the deactivated and the active part of the cartridge is quite sharply delimited.

The effect of the method according to the invention is shown in the accompanying drawings of FIGS. 1 and 2.

The process of catalyst deactivation in the methanization reactor is shown in Figure 1, which shows the temperature profiles in the catalyst bed of catalyst Ki with a NiO content of 24% by weight. and catalyst K2 with 39 wt. NiO as a function of operating time t _{i (where} T is the temperature in the catalyst bed, t _R, are quantities proportional to the time of operation and the corresponding curves show the temperature profile along the bed 1 and the operating time t (t _f), with t _{i +} >> ie curves marked tj (tj ·) show simultaneously the deactivation rate of catalysts K1 and K2 and determine the interface between the deactivated and non-deactivated part of the catalyst.

S fully. Under standard operating conditions, the temperature profile in the catalyst bed depends on its activity. The activity and especially its lifetime, ie especially the resistance to catalytic poisons, are primarily influenced by the content of Ni in the catalyst. The lower the NiO content of the catalyst, the faster the temperature profile in the catalyst bed shifts downstream and the temperature rise gradient decreases.

For a certain charge of the reactor and with constant hydrogen throughput of the same composition both in the content of oxygen substances and poisons, the course of deactivation up to the first oxygen poison penetration is practically linear, expressed in time-effective volumetric velocity which is process gas flow in m _n ³ based on the volume of the non-deactivated portion of the catalyst charge. This dependence with regard to the CO and CO 2 content in the gas after methanation is shown in Fig. 2, which shows the time course of methanation efficiency again for both mentioned types of catalysts with a content of NiO of 24% Ki and 39% K2, where

Vij - effective gas volumetric velocity on catalyst Kt,

V _2i - dtto for catalyst K2, ti-tj "- quantities proportional to the operating time.

In both figures, ti represents the moment of starting a new cartridge and t3 ', t3 represent a practically usable time pool, ie the operating time during which the oxygen content of the gas is below 10 ppm vol. reaction temperatures. Accordingly, for a given reactor system, the time interval between two partial or complete catalyst exchanges is determined by the type of catalyst, its loading with the process gas and the purity of the process gas, which is determined by the poisons of both catalytic and porous catalyst pores. The activity of catalysts with different NiO content is shown in Example 1, which presents the results of measurement of activity in a laboratory reactor and results of operational tests of the use of a catalyst with a NiO content of 24 wt. NiO was then used in Examples 2 and 3.

Example 1

Laboratory comparison of catalyst activity with different NiO content of 1 to 24%; 2 to 38 wt.

250 ml of the original grain catalyst was charged to a lamoratory non-isothermal non-adiabatic reactor and reduced with pure hydrogen for 16 hours at a gradually increasing temperature from 20 to 300 to 350 ° C at a hydrogen flow rate of 500 liters per hour and pressure

MPa. After the reduction was introduced hydrogen containing 0.8% CO and 80 ppm vol., And CoA at a pressure of 3 MPa and a volume loading of 10 000 h ^_1 (gas 1 t / 1 t katal./hj monitored intersection of CO and CO as a function of decreasing temperature.

Catalyst 1 2

Penetration temperature in ° C (Contents)

CO and CO2 above 10 ppm)

Example 2

Operational results with up to 24% NiO catalyst

The 9 m ³ catalyst methanization reactor operated under the following conditions:

Input gas composition:

0.15% by mol. CO2,

0.40 mol%. WHAT,

97.0 mol%. H2,

2.45 mol%. inerty.

Volumetric speed 5800 h ^_1 ; inlet temperature 285 ° C; increase in temperature by reaction heat of methanation 38 ° C.

The feed gas was preheated to the reaction temperature by both an exchanger system and an electric preheater. The temperature profile was monitored by measuring the temperature with thermocouples distributed over the length of the catalyst bed. The residual CO + COa content was below ppm ·. After deactivation of the 40% filling, and at a space velocity of 9600 h ^_1, based on nedesaktivovanou filling portion was penetration of CO and CO: Increasing the inlet temperature helped only temporarily, and it was necessary to replace the catalyst charge.

Example 3

Operational results with combined catalysts 1 and 2

From the reactor of Example 2, 4 m ^{3 of} catalyst 1 were removed and replaced with 4 m ^{3 of} catalyst 2 with 39% NiO. After heating and reducing the new charge together with the old part, the reactor was brought to operating conditions as in Example 2. Only the inlet temperature was gradually reduced until an inadmissible CO + CO 2 content appeared at the outlet, which was reached at 200 ° C. For reasons of operational reliability, the operating temperature at the reactor inlet was then increased to 220 to 230 ° C, with the oxygen content at the outlet being below 1 ppm. Energy consumption has been reduced from 460 to 210 kW.

Claims (2)

SUBJECT 1. A process for the removal of oxygenated carbon compounds from industrial hydrogen by hydrogenating them to methane on nickel supported catalysts or supported catalysts containing precious metals of Group 8 of the Periodic Table of Elements which is fed to the reaction space in oxidic or pre-reduced form, hydrogen is applied to a catalyst layer consisting of at least two kinds of catalyst with different active nickel content or modified noble metals of Group 8, which are reduced by hydrogen or technical hydrogen at temperatures gradually rising to 300 to 350 prior to the initiation of the methanation reaction ^C C at a pressure of 0.1 to 10 MPa and a volumetric velocity of reducing gases of 250 to 3000 v / v / h for at least 12 hours, at a pre-reduced at least 4 hours, after which the catalyst bed temperature of the invention is reduced to 190 to 270 ° C, preferably 210 to 250 ° C, at which the methanation purification of technical hydrogen to 5 ppm of oxygen in the gas leaving the catalyst bed begins at a volume rate of 5000 to 10,000 v / v. of catalyst per hour, monitoring the aging and poisoning of the catalyst bed by measuring the temperature profile in the bed and reaching 9000 to 12,000 v / v. of active catalyst, the reaction is stopped and the deactivated catalyst is replaced with active. 2. Process according to claim 1, characterized in that the catalyst bed inlet layer comprises a catalyst with the highest nickel content, preferably 30 to 50% by weight. % NiO, and the exit layer comprises a catalyst with the lowest nickel content, preferably 10 to 25 wt. NiO, and / or catalyst partially deactivated in the previous operating cycle.