Title of Invention

"AN ADSORBENT COMPOSITION, A PROCESS FOR THE PREPARATION THEREOF AND A PROCESS FOR REMOVAL OF HYDROGEN SULPHIDE IMPURITIES FROM A GASEOUS FEED STOCK"

Abstract An adsorbent composition for use in the removal of hydrogen sulphide impurities from a gaseous feedstock is disclosed. The adsorbent comprises a waste from a refmery applcation and an oxide of a trivalent metal, said waste from a refinery application and said oxide of a trivalent metal being present in a ratio of from 4:1 to 19:1. Also disclosed are process for preparing such adsorbents and process for the removal of hydrogen sulphide impurities from a gaseous feedstock.
Full Text Field of invention
The present invention relates to a synergistic adsorbent composition for use in the removal of hydrogen sulphide (H2S) from biogas, natural gas, acid gases and other similar gaseous feedstock. The present invention relates to a process for recovery of elemental sulfur from natural gas, biogas and acid gases. More particularly, the present invention relates to a process for the recovery of elemental sulfur from bio gas, natural gas and acid gases by treating such gases with an mixture of a refinery waste product and a metal oxide and then regenerating said mixture. The process of the invention comprises removal of hydrogen sulphide (H2S) from biogas, natural gas and acid gases. The present invention also relates to a process for sweetening of biogas, natural gas and acid gases by absorption and adsorption of H2S from such gases. The present invention also relates to removal of H2S and moisture present as impurities by a synthetic synergistic composition comprising of waste from a refinery application and oxide of a trivalent metal. Background of the invention
Prior art teaches several complicated processes for removal of hydrogen sulfide from gaseous feedstocks. However, these processes are cumbersome, complex and expensive. Some of the known processes are also hazardous. Accordingly, there is a tremendous need for a simple and cost effective process, which almost completely eliminates hydrogen sulfide impurities from gaseous feedstocks and brings the impurity levels to levels acceptable in the industry. Objects of the invention
It is the principal object of the present invention to remove H2S from gaseous feedstocks by a process, which avoids the drawbacks of the prior art.
It is the another object of the present invention to remove H2S from gaseous feedstocks such as biogas, natural gas and acid gases by a low cost process.
Another object of the invention is to utilize the waste of a refinery application for hydrogen sulfide removal, and thereafter recovery of elemental sulfur by regeneration of the mixture.
It is another object of the invention to provide a method for removal of H2S from biogas, natural gas and acid gases where that is economical and efficient.
It is a further object of the invention to provide a process for removal of H2S from biogas, natural gas and acid gases that is safe, requires less time and is easy to operate and results in a final pure product with minimal contamination.
It another important object of the present invention to provide an adsorbent composition for use in the removal of H2S from gaseous feedstocks. Summary of the invention
The present invention is based on the use of a combination of agents, which act synergistically to provide effective removal of H2S from biogas, natural gas and acid gases. The invention is based on the surprising interaction and results obtained by the use of a synergistic adsorbent composition comprising of a synthetic mixture of wastes from one of refinery applications and oxide of a trivalent metal.
It has been now surprisingly found that this adsorbent composition when contacted with gases containing hydrogen sulphide as impurities reduces the concentration of the contaminants to less than 10 ppmv while requiring less residence time. Another significant advantage of using the synergistic mixture of the invention for removal of H2S is that the level of equipment is low thereby reducing the costs of the process. Thus, the process of the invention is suitable for large-scale commercial operations. Since the components of the mixture are readily available, the net costs of the process are ftirther reduced.
The mixture of waste from one of refinery applications and oxide of a trivalent metal is neither a simple admixture nor a product of a chemical reaction but a synergistic composition showing improved and unexpected properties.
It is observed that the residence time of gas for removal of H2S is low. In addition, the metal oxide acts as an exothermic agent, and helps in maintaining the bed temperature. This enables the temperature in the sulphur pit to be maintained at ambient. The concentration of the hydrogen sulphide in the final product is Accordingly, the present invention provides an adsorbent composition for use in the removal of hydrogen sulphide impurities from a gaseous feedstock comprising a waste from a refinery application and an oxide of a trivalent metal, said waste from a refinery apphcation and said oxide of a trivalent metal being present in a ratio of from 4:1 to 19:1
The invention also relates to a process for preparing a adsorbent composition for removal of hydrogen sulfide from gaseous feedstocks, which comprising mixing in any conventional manner a waste from a refmery application and oxide of a trivalent metal in a ratio of 4:1 to 19:1.
In a preferred embodiment, adsorbent is a synthetic synergistic mixture of a waste from a refinery application selected from a transition metal embedded material and an oxide of a trivalent metal selected from an oxide of a transition metal. Preferably, said

transition metal is selected from the group consisting of the elements present in group Vni in the periodic table.
In another embodiment, the present invention also relates to a process for the removal of H2S from a gaseous stream feedstock containing 10,000 - 30,000 ppmv of H2S or less wherein the gaseous feed is passed through an adsorbent, wherein in said adsorption system comprising a waste from a refinery application and an oxide of a trivalent metal, said waste from a refinery apphcation and said oxide of a trivalent metal being present in a ratio of from 4:1 to 19:1
Preferably, the concentration of H2S leaving the absorber is in the range or from about 10- lOOppmv.
In another important preferred feature, the gaseous feed is passed through the adsorbent at a temperature of 10°C about 50° C and a pressure of 1.2 - 70 kg/cm^a
In another preferred embodiment, a major part of the H2S in the feedstock is adsorbed physically by the transition metal embedded material.
In another preferred embodiment, a part of the H2S in the feedstock is chemisorbed by the oxide of a transition metal.
In a preferred feature, the feedstock is in the gaseous state. Preferably, the feedstock consists of biogas, natural gas or acid gases.
In another preferred embodiment, the synthetic mixture of the transition metal embedded material and the oxide of transition metal is regenerated by air after adsorption.
In a feature of the invention, the regeneration increases the bed temperature of the absorber by 5-10°C.
In another embodiment, the adsorbed H2S is partly converted to elementary sulphur. Preferably, a part of adsorbed H2S is released to as molecular H2S.
In another embodiment, the adsorption capacity of the adsorbent is in the range or from 0.2 - 1.0 kg of H2S in 100 Kg of adsorbent. Detailed description
the present invention provides an adsorbent composition for use in the removal of hydrogen sulphide impurities from a gaseous feedstock comprising a waste from a refinery apphcation and an oxide of a trivalent metal, said waste from a refinery application and said oxide of a trivalent metal being present in a ratio of from 4:1 to 19:1
The invention also relates to a process for preparing a adsorbent composition for removal of hydrogen sulfide from gaseous feedstocks, which comprising mixing in any
conventional manner a waste from a refinery application and oxide of a trivalent metal in a ratio of 4:1 to 19:1.
The present invention also relates to a process for the removal of H2S from a gaseous stream feedstock containing 10,000 - 30,000 ppmv of H2S or less wherein the gaseous feed is passed through an adsorbent, wherein in said adsorption system comprising a waste from a refinery appUcation and an oxide of a trivalent metal, said waste from a refinery appUcation and said oxide of a trivalent metal being present in a ratio of from 4:1 to 19:1
It is observed that the residence time of gas for removal of H2S is low. In addition, the metal oxide acts as an exothermic agent, and helps in maintaining the bed temperature. This enables the temperature in the sulphur pit to be maintained at ambient. The concentration of the hydrogen sulphide in the final product is The mixture is regenerative and regeneration is carried out by aeration. The regeneration process results in the production of elemental sulfur which phenomenon has not been observed in the art so far. The mixture is also found to be hydrophilic and therefore enables the removal of moisture from the feed gas, thereby resulting in improved purification. The regeneration process is carried out at ambient temperature. The mixture does not absorb hydrocarbon during the absorption and adsorption of hydrogen sulphide from feed gas.
The present invention involves the use of a synthetic mixture of waste from a refinery application and oxide of a trivalent metal as an absorbent and adsorbent to reduce the concentration of hydrogen sulphide from feed gas. The mixture in a fixed bed reactor is charged with the feed gas containing hydrogen sulphide and water. The treated gas from the reactor is analyzed for hydrogen sulphide and water. The operation is continued till the bed is saturated.
The hydrogen sulfide is chemisorbed on the surface of the mixture as well as diffused into the lattice thereof The refinery waste used is a spent zeolite catalyst from a FCC process. It is observed that unlike a fresh zeolite catalyst, the rate of adsorption is much higher for the spent catalyst. The bed is regenerated by air passing continuously into it. After regeneration the bed is recharged with acid gas. The H2S removal efficiency, the saturation point of the adsorbent and regeneration characteristics have been evaluated. Hydrocarbon adsorption ability of the adsorbent has been tested and found to be quite high.
Without wishing to be bound by any theory, it is believed that the process works by chemisorption of the hydrogen sulfide onto the surface of the adsorbent as well as diffusion thereof into the lattice of the zeolite. In addition, the mixture utilizes the presence of Fe on the surface and transition metals in the lattice to provide a better rate of adsorption of hydrogen sulfide from the feed gas. Surprisingly, it is also found that the regeneration of the mixture by aeration results in the formation of elemental sulfur. The present invention will now be described with reference to the following Examples. The disclosure contained herein is representative of embodiments of the invention and are not to be construed as limiting the scope of the invention in any manner. Example 1
14" tall perplex column of 3" diameter was used as reactor. The H2S gas generated in a kip's apparatus was fed at the bottom of the reactor. To ensure the proper distribution of the gas inside the bed, a bed of sand (size >150 mesh) with 1 - 1.5" height was set at the bottom of the column. A bed of a the transition metal embedded material was built over the sand bed. The size of the catalyst is greater than 250 mesh and less than 150 mesh. The height of the bed was 12". The clean gas was vented out from top of the reactor. The gas coming out of the reactor was put inside an alkaline solution present in a beaker. During regeneration, the air was passed through the bed fi-om top to bottom using a blower. The airflow rate was controlled by a rotameter of range 0-20 SCFH.
The transition metal embedded material was properly screened by sieve shaker. -150 mesh to +250 mesh fraction of the catalyst was used as adsorbent. The reactor was filled up with the adsorbent over the sand bed and placed vertically. The height of the bed was -12".
Weighted iron sulphide sticks were put into a kips apparatus of capacity of 500ml and the sticks were emerged in water. The concentrated sulphuric acid was added gradually into the kip-apparatus. A vigorous reaction, which formed H2S inside it, appeared instantaneously. The H2S produced was passed through the bottom of bed continuously. The gas got absorbed inside the bed. The outlet tube was immersed in 0.01 (N) silver nitrate solution to find the saturation point. At the saturation point, the solution was converted to black. At saturation point, gas supply was stopped and kip-apparatus was properly washed out and collected the remaining iron sulphide soUd and weighted after drying. The difference of weight was used to compute the equilibrium absorption capacity of the catalyst towards absorption of H2S.
After absorption process, the bed was subjected to regeneration by aeration. The bed was regenerated by controlled flow of air from blower. The air was passed through top to bottom, to avoid distortion of the bed. The air was passed with slightly positive pressure at ambient temperature. The H2S was come out of the bed with air. The end point of the regeneration was indicated by no change in colour of dilute silver nitrate solution. The adsorption and regeneration period was maintained more or less equal. The regenerated bed was repeatedly used for adsorption of H2S. It was noticed that there was no much change in equilibrium adsorption capacity of the catalyst for adsorption of H2S. The results are shown in Table 1. Example 2
3' 6" tall perplex column of 4" diameter was used as reactor at a biogas plant. The reactor had three equal beds. Bottom two beds were filled with a synthetic mixture of the transition metal embedded material and an oxide of a transition metal. Biogas from a blower was fed at the bottom of the reactor with positive pressure (1.2 Kg/cm2A). Biogas contains methane (CH4, 62 - 70%V), carbon dioxide (CO2, 30 - 34%V), H2S (1 - 2.4%V) and water (saturated). To ensure the proper distribution of the gas inside the bed, a bed of sand (size >150 mesh) with 1 - 1.5" height was set at the bottom of the column. The treated biogas coming out of the reactor was vented to atmosphere. The bed was not saturated completely and regeneration was done by air at ambient temperature using a blower. The air pressure was 1.4 Kg/cm2A. The results are shown in Table 2
(TABLE REMOVED)


Note -1: Composition:
Metal oxide =8-10%(wt)
Spent FCC catalyst = 90 - 92%(wt)
Note - 2: Operating pressure =1.2-1.5 Kg/cm2a
Operating temperature = Ambient
Note - 3: Feed stock = Biogas from molasses
Note - 4: Bed adsorption capacity =0.8 wt%




We claim:
1. An adsorbent composition for use in the removal of hydrogen sulphide impurities from
a gaseous feedstock comprising: '
(i) a waste from a refinery application wherein said waste from a refinery application
comprises a transition metal embedded material; and
(ii) an oxide of a trivalent metal selected from an oxide of a transition metal wherein
said transition metal is selected from the group consisting of the elements of group
VIII in the periodic table;
wherein said waste from a refinery application and said oxide of a trivalent metal
being present in a ratio of from 4: 1 to 19: 1.
2. A process for 'preparing an adsorbent composition for removal of hydrogen sulfide
from gaseous feedstock, which comprises mixing a waste from a refinery application
I
and oxide of a trivalent metal in a ratio of 4: 1 to 19: 1 ;
wherein said waste from a refinery application comprises a transition metal embedded
material and said oxide of a trivalent metal is selected from an oxide of a transition
metal wherein said transition metal is selected from the group consisting of the
elements of group VIII in the periodic table.
3. A process for the removal of H2S from a gaseous stream feedstock containing 10,000 -
30,000 ppmv of H2S or less using the adsorbent composition as claimed in claim 1,
wherein the gaseous feed is passed through said adsorbent composition at a
temperature of 10°C to 50°C and a pressure of 1.2 to 70 kg/cm2a.
4. A process as claimed in claim 3,'wherein the concentration of H2S leaving the absorber
is in the range or from about 10-1 00 ppmv.

Documents:

99-DEL-2003--1-GPA-(01-08-2013).pdf

99-DEL-2003-1-Correspondence-Others-(01-08-2013).pdf

99-del-2003-Abstract-(08-10-2012).pdf

99-del-2003-abstract.pdf

99-DEL-2003-Claims-(05-08-2013).pdf

99-del-2003-Claims-(08-10-2012).pdf

99-DEL-2003-Claims-(10-07-2013).pdf

99-del-2003-claims.pdf

99-DEL-2003-Correspondence Others-(05-08-2013).pdf

99-del-2003-Correspondence-Others-(06-11-2012).pdf

99-del-2003-Correspondence-Others-(08-10-2012).pdf

99-DEL-2003-Correspondence-Others-(10-07-2013).pdf

99-del-2003-Correspondence-Others-(18-10-2012).pdf

99-del-2003-Correspondence-Others-(23-10-2012).pdf

99-del-2003-correspondence-others.pdf

99-del-2003-correspondence-po.pdf

99-del-2003-description (complete).pdf

99-del-2003-description (proviisonal).pdf

99-del-2003-form-1.pdf

99-del-2003-form-13.pdf

99-del-2003-form-18.pdf

99-del-2003-Form-2-(08-10-2012).pdf

99-del-2003-form-2.pdf

99-del-2003-form-3.pdf

99-del-2003-form-4.pdf

99-del-2003-form-5.pdf

99-del-2003-gpa.pdf

99-del-2003-petition-138.pdf


Patent Number 256954
Indian Patent Application Number 99/DEL/2003
PG Journal Number 34/2013
Publication Date 23-Aug-2013
Grant Date 17-Aug-2013
Date of Filing 06-Feb-2003
Name of Patentee ENGINEERS INDIA LIMITED
Applicant Address ENGINEERS INDIA BHAVAN, 1 BHIKAJI CAMA PLACE, NEW DELHI-110 066, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 SARKAR, DIPAK KUMAR ENGINEERS INDIA LIMITED R&D COMPLEX, SECTOR 16, GURGAON 122001, HARYANA, INDIA.
2 SAHU, ARUNABHA ENGINEERS INDIA LIMITED R&D COMPLEX, SECTOR 16, GURGAON 122001, HARYANA, INDIA.
3 DATTA, SAMIR KUMAR ENGINEERS INDIA LIMITED R&D COMPLEX, SECTOR 16, GURGAON 122001, HARYANA, INDIA.
4 SONI, ADARSH ENGINEERS INDIA LIMITED R&D COMPLEX, SECTOR 16, GURGAON 122001, HARYANA, INDIA.
5 SEN PRODIP KUMAR ENGINEERS INDIA LIMITED R&D COMPLEX, SECTOR 16, GURGAON 122001, HARYANA, INDIA.
PCT International Classification Number C01B 17/027
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA