Hydro Treating
Catalytic hydrotreating is the most common process units in petroleum refineries and have an especial NoDoC cost estimation model. NoDoC considers it as a catalytically hydrogenation process used to remove about 90% of contaminants such as nitrogen, sulfur, oxygen, and metals from liquid petroleum fractions.
NoDoC presents the model such that if these contaminent not removed from the petroleum fractions as they travel through the refinery processing units, can have detrimental effects on the equipment, the catalysts, and the quality of the finished product. Typically, hydrotreating is done prior to processes such as catalytic reforming so that the catalyst is not contaminated by untreated feedstock.
NoDoC shows that hydrotreating is also used prior to catalytic cracking to reduce sulfur and improve product yields, and to upgrade middle-distillate petroleum fractions into finished kerosene, diesel fuel, and heating fuel oils. In addition, hydrotreating converts olefins and aromatics to saturated compounds. Hydrotreating is applied to a wide range of feedstocks, from naphtha to reduced crude. When the process is employed specifically for sulfur removal it is usually called hydrodesulfurization, or HDS.
Hydrotreating for sulfur removal is called hydrodesulfurization. In a typical catalytic hydrodesulfurization unit, the feedstock is deaerated and mixed with hydrogen, preheated in a fired heater (600°-800° F) and then charged under pressure (up to 1,000 psi) through a fixed-bed catalytic reactor. In the reactor, the sulfur and nitrogen compounds in the feedstock are converted into H2S and NH3. The reaction products leave the reactor and after cooling to a low temperature enter a liquid/gas separator. The hydrogen-rich gas from the high-pressure separation is recycled to combine with the feedstock, and the low-pressure gas stream rich in H2S is sent to a gas treating unit where H2S is removed. The clean gas is then suitable as fuel for the refinery furnaces. The liquid stream is the product from hydrotreating and is normally sent to a stripping column for removal of H2S and other undesirable components. In cases where steam is used for stripping, the product is sent to a vacuum drier for removal of water.NoDoC considers hydrodesulfurized products are blended or used as catalytic reforming feedstock.
Catalysts developed for hydrotreating include cobalt and molybdenum oxides on alumina, nickel oxide, nickel thiomolybdate, tungsten and nickel sulfides, and vanadium oxide. The cobalt and molybdenum oxides on alumina catalysts are in most general use today because they have proven to be highly selective,easy to regenerate, and resistant to poisons. They must be activated by converting the hydrogenation metals from the oxide to the sulfide form. Cobalt–molybdenum catalysts are selective for sulfur removal and nickel–molybdenum catalysts are selective for nitrogen removal, although both catalysts will remove both sulfur and nitrogen.
The main hydrotreating reaction is that of desulfurization but many others take place to a degree proportional to the severity of the operation.
Typical reactions that are included in NoDoC are:
- Desulfurization
a)Mercaptans: RSH + H2 ? RH + H2S
b)Sulfides: R2S + 2H2 ? 2RH + H2S
c)Disulfides: (RS)2 + 3H2 ? 2RH + 2H2S
d)Thiophenes:
- Denitrogenation
a)Pyrrole: C4H4NH +?C4H10 + NH3
b)Pyridine: C5H5N + 5H2 ? C5H12+ NH3
- Deoxidation
a)Phenol: C6H5OH + H2 ? C6H6 + H2O
b)Peroxides: C7H13OOH + 3H2 ? C7H16 + 2H2O
- Dehalogenation
Chlorides: RCl + H2 ? RH + HCl.
- Hydrogenation
Pentene: C5H10 + H2 ? C5H12
- Hydrocracking
C10H22+ H2 ? C4H10 + C6H14
NoDoC presents the model such that if these contaminent not removed from the petroleum fractions as they travel through the refinery processing units, can have detrimental effects on the equipment, the catalysts, and the quality of the finished product. Typically, hydrotreating is done prior to processes such as catalytic reforming so that the catalyst is not contaminated by untreated feedstock.
NoDoC shows that hydrotreating is also used prior to catalytic cracking to reduce sulfur and improve product yields, and to upgrade middle-distillate petroleum fractions into finished kerosene, diesel fuel, and heating fuel oils. In addition, hydrotreating converts olefins and aromatics to saturated compounds. Hydrotreating is applied to a wide range of feedstocks, from naphtha to reduced crude. When the process is employed specifically for sulfur removal it is usually called hydrodesulfurization, or HDS.
Hydrotreating for sulfur removal is called hydrodesulfurization. In a typical catalytic hydrodesulfurization unit, the feedstock is deaerated and mixed with hydrogen, preheated in a fired heater (600°-800° F) and then charged under pressure (up to 1,000 psi) through a fixed-bed catalytic reactor. In the reactor, the sulfur and nitrogen compounds in the feedstock are converted into H2S and NH3. The reaction products leave the reactor and after cooling to a low temperature enter a liquid/gas separator. The hydrogen-rich gas from the high-pressure separation is recycled to combine with the feedstock, and the low-pressure gas stream rich in H2S is sent to a gas treating unit where H2S is removed. The clean gas is then suitable as fuel for the refinery furnaces. The liquid stream is the product from hydrotreating and is normally sent to a stripping column for removal of H2S and other undesirable components. In cases where steam is used for stripping, the product is sent to a vacuum drier for removal of water.NoDoC considers hydrodesulfurized products are blended or used as catalytic reforming feedstock.
Catalysts developed for hydrotreating include cobalt and molybdenum oxides on alumina, nickel oxide, nickel thiomolybdate, tungsten and nickel sulfides, and vanadium oxide. The cobalt and molybdenum oxides on alumina catalysts are in most general use today because they have proven to be highly selective,easy to regenerate, and resistant to poisons. They must be activated by converting the hydrogenation metals from the oxide to the sulfide form. Cobalt–molybdenum catalysts are selective for sulfur removal and nickel–molybdenum catalysts are selective for nitrogen removal, although both catalysts will remove both sulfur and nitrogen.
The main hydrotreating reaction is that of desulfurization but many others take place to a degree proportional to the severity of the operation.
Typical reactions that are included in NoDoC are:
- Desulfurization
a)Mercaptans: RSH + H2 ? RH + H2S
b)Sulfides: R2S + 2H2 ? 2RH + H2S
c)Disulfides: (RS)2 + 3H2 ? 2RH + 2H2S
d)Thiophenes:
- Denitrogenation
a)Pyrrole: C4H4NH +?C4H10 + NH3
b)Pyridine: C5H5N + 5H2 ? C5H12+ NH3
- Deoxidation
a)Phenol: C6H5OH + H2 ? C6H6 + H2O
b)Peroxides: C7H13OOH + 3H2 ? C7H16 + 2H2O
- Dehalogenation
Chlorides: RCl + H2 ? RH + HCl.
- Hydrogenation
Pentene: C5H10 + H2 ? C5H12
- Hydrocracking
C10H22+ H2 ? C4H10 + C6H14
