Multi-stage countercurrent hydrotreating process

Abstract

A multi-stage process for removing heteroatoms, particularly organic sulfur and nitrogen components, from liquid petroleum and chemical streams. The feedstream flows countercurrent to the flow of a hydrogen-containing treat gas and is reacted with a first catalyst which is relatively tolerant to sulfur and nitrogen, such as a CoMo supported catalyst. When the level of organic sulfur in the feedstream is less than about 3,000 wppm and the level of organic nitrogen is less than about 1,000 wppm, the feedstream is reacted with said counter flowing hydrogen-containing treat gas in the presence of a catalyst comprised of Ni and a Group VIA metal selected from Mo, W, or both, on a refractory support. The reaction vessel preferably contains vapor and optionally liquid by-pass means in one or more of the catalyst beds.

What is claimed is:  
     
         1 . A multi-stage process for removing sulfur and nitrogen containing components from petroleum and chemical feedstreams containing at least one of said components, in the presence of a hydrogen-containing treat gas flowing countercurrent to the flow of said feedstream, the process which comprises: 
 reacting said feedstock in a first reaction stage with said hydrogen-containing treat gas in the presence of a hydrotreating catalyst comprised of at least one Group VIII metal and at least one Group VIA metal on a refractory support, at hydrotreating conditions, until the reacted feedstock contains less than about 3,000 wppm sulfur and less than about 1,000 wppm nitrogen;    reacting said treated feedstock from said first reaction stage in a second stage with counterflowing hydrogen-containing treat gas in the presence of a catalyst comprised of Ni and one or both of a metal selected from Mo and W, on a refractory support.    
     
     
         2 . The process of    claim 1    wherein the hydrotreating conditions include temperatures ranging from about 100° C. to about 400° C. at pressures from about 50 psig to about 2,000 psig.  
     
     
         3 . The process of    claim 1    wherein the Group VIII metal is Co and the Group VIA metal is Mo.  
     
     
         4 . The process of    claim 1    wherein the first reaction zone is operated in a co-current mode wherein the feedstream and the treat gas are both flowing in the same direction.  
     
     
         5 . The process of    claim 1    wherein both the first and the second reaction stages are operated in countercurrent mode wherein the feedstream and the treat gas flow countercurrent to each other.  
     
     
         6 . The process of    claim 1    wherein the amount of Group VIII metal is from about 2 wt. % to 20 wt. %, based on the total weight of the catalyst.  
     
     
         7 . The process of    claim 1    wherein the amount of Group VIA metal is from about 5 to about 50 wt. %, based on the total weight of the catalyst.  
     
     
         8 . The process of    claim 3    wherein  2  wherein the Group VIII metal is Co and the Group VIA metal is Mo.  
     
     
         9 . A multi-stage process for removing sulfur and nitrogen containing components from petroleum and chemical feedstreams containing at least one of said components, in the presence of a hydrogen-containing treat gas flowing countercurrent to the flow of said feedstream, the process which comprises: 
 reacting said feedstock in a first reaction stage with said hydrogen-containing treat gas in the presence of a hydrotreating catalyst comprised of at least one Group VIII metal and at least one Group VIA metal on a refractory support, at hydrotreating conditions, until the reacted feedstock contains less than about 3,000 wppm sulfur and less than about 1,000 wppm nitrogen;    reacting said treated feedstock from said first reaction stage in a second stage with counterflowing hydrogen-containing treat gas in the presence of a catalyst comprised of Ni and one or both of a metal selected from Mo and W, on a refractory support; and    reacting the treated feedstock from said second reaction stage in a third reaction stage in the presence of a hydrogen-containing treat gas and an aromatics hydrogenation catalyst comprised of a noble metal on a refractory support at hydrogenation conditions.    
     
     
         10 . The process of    claim 9    wherein the hydrotreating conditions include temperatures ranging from about 100° C. to about 400° C. at pressures from about 50 psig to about 2,000 psig.  
     
     
         11 . The process of    claim 10    wherein the Group VIII metal is Co and is present in an amount ranging from about 2 wt. % to 20 wt. %, and the Group VIA metal is Mo in an amount ranging from about 5 to 50 wt. %, based on the total weight of the catalyst.  
     
     
         12 . The process of    claim 11    wherein the first reaction zone is operated in a co-current mode wherein the feedstream and the treat gas are both flowing in the same direction.  
     
     
         13 . The process of    claim 11    wherein both the first reaction stage is operated in co-current mode and the second and third reaction stages are operated in countercurrent mode wherein the feedstream and the treat gas flow countercurrent to each other.  
     
     
         14 . The process of    claim 11    wherein the all three stages are operated in countercurrent mode.