title: Nickel removal from nickel-5,10,15,20-tetraphenylporphine using supercritical water in absence of catalyst: a basic study.
abstract: Reactions of nickel-5,10,15,20-tetraphenylporphine (Ni-TPP) were studied in supercritical water in the presence of toluene without the addition of any catalyst, H(2) or H(2)S that is called a green process. The objective of this study was to remove nickel from Ni-TPP, the most common metal compound present in heavy crude, in high extent at low reaction time. All experiments were carried out in an 8.8 mL batch reactor fabricated from hastelloy C-276. The ability of supercritical water (SCW) to remove nickel from Ni-TPP was studied at temperatures of 450-490 °C and water partial pressures of 25-35 MPa. Water partial pressure had no effect on overall conversion at temperatures of 450 °C and a reaction time of 60 min. The overall Ni-TPP conversion was 89.80%, a figure above that of previous catalytic studies. The percentage of nickel removal was estimated as a function of reaction time and temperature. It were temperature 490 °C and pressure 25 MPa at reaction time 90 min where 65.68% nickel were removed by the action of SCW and toluene, as a co-solvent. It was determined that Ni-TPP undergoes a series of reactions, ending in demetallation and ring fragmentation. The obtained results suggest that supercritical water has a capability to remove nickel from Ni-TPP.
authors.affiliation: Graduate School of Science and Technology, Kumamoto University, Japan.
authors.forename: Pradip Chandra
authors.initials: PC
authors.lastname: Mandal
authors.lastname: Wahyudiono
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Sasaki
authors.forename: Motonobu
authors.initials: M
authors.lastname: Goto
mesh_terms: D002384:Catalysis; D007700:Kinetics; D009532:Nickel / Q000302:isolation & purification*; D011166:Porphyrins / Q000737:chemistry*; D013696:Temperature; D014867:Water
chemical_list: D011166:Porphyrins; D014867:Water; D009532:Nickel; C049692:tetraphenylporphine