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• Posted By : admes liliy
• Posted On : Apr 18, 2023
• Views : 48
• Category : General
• Description : The oxides used were reagent grade commercial products (V2O5, MgO, ZnO, Fe2O3, La2O3, CuO) or from appropriate salts. Mn3O4, NiO and Co3O4 is obtained from basic carbonates by heating at 803 K 3 hours, identified by infrared spectroscopy [11]. Decompose to get Cr20 3 Hydroxide Cr(OH) 3 at 673 K. 2.2.

Overview

• The oxides used were reagent grade commercial products (V2O5, MgO, ZnO,
  Fe2O3, La2O3, CuO) or from appropriate salts. Mn3O4, NiO and
  Co3O4 is obtained from basic carbonates by heating at 803 K
  3 hours, identified by infrared spectroscopy [11]. Decompose to get Cr20 3
  Hydroxide Cr(OH) 3 at 673 K. calcium pantothenate
  2.2. Catalyst test
  Catalytic experiments were performed in a flow system on a fixed bed of 2 g
  catalyst. The catalyst was activated under a gas flow of 723 K and used
  Argon before the experiment. Reagent grade cyclohexanol vapor
  Introduce using a calibrated syringe and evaporator. concentrated reaction
  Product analysis by GC on a 2 m silanized chromosorb W column
  60-80 mesh, 15% DC 550, 403K.
  All experiments were performed at 673 K and WHSV 2 hr −1 . Some
  Oxides (e.g. Mn3O4) are inactive to cyclohexanol below 673
  K. Results are summarized in Table 1.
  3. Results and discussion
  Microcalorimetric studies [3] allow the classification of oxides
  Divided into 3 groups: acidic oxides A; basic oxides B; acidic and basic oxides A-B.
  CP Bezouhanova, M.A. Al-Zihari / Test reactions for acid-base properties
  Table 1
  Conversion of cyclohexanol over oxide catalysts. Temperature 673 K, LHSV 2 h-1
  247
  Catalyst product (wt.%)
  C-Hexene C-Hexanol C-Hexanone Phenol
  Magnesium Oxide - 64.0 30.6 1.4
  Zinc oxide 3.9 26.1 67.6 -
  Iron dioxide 3 8.9 65.9 22.7 1.0
  Manganese 304 3.3 75.0 18.0 1.2
  Zirconia 5 99.7 - - -
  Cr20 3 16.5 42.1 36.4 -
  Copper oxide - 17.7 65.3 11.3
  Co3O4 11.7 50.3 26.5 4.3
  Nickel oxide 3.7 46.6 40.2 6.3
  La20 3 1.2 79.9 16.6 -
  Our experiments with cyclohexanol showed that V2O5 is a typical acid,
  And MgO is a typical base. This is consistent with the results in [3].
  Considering that the heterogeneous dissociation of hydrogen can
  occurs on MgO [12], hydrogen extraction from cyclohexanol can be
  Assumptions:
  Hydrogen +
  Mg----~O Magnesium
  > +
  H + HMg--d--lVlg
  Metal cations serve as Lewis active sites.
  No Broensted acid sites are found in CuO. NiO and Mn3O4 show small
  dehydration activity.
  According to the results in [3], V205 has only Brunsted acid
  site, since the only reaction product is cyclohexene. Acid sites also occur in
  Cr2O3, C03O4, Fe2O3, ZnO, Mn3O4, NiO, La20 3 in order
  Activity.
  ZnO is considered as a solid base [3,13], but some acidic properties have been
  also established [14]. The most active materials in dehydrogenation are ZnO and
  Copper oxide. It is well known [15] that Zn- and Cu-catalysts find industrial application
  Dehydrogenation of cyclohexanol to cyclohexanone at 673-723 K and atmospheric pressure. Under our experimental conditions, CuO and NiO also dehydrogenated cyclohexanol to phenol.
  Although dehydrogenation of alcoholic hydroxyl groups may proceed
  Hydrogen accepting sites with fundamental features - oxygen atoms from oxides
  248 C.P. Bezuhanuwa, AIM. Al-Zihari / Acid-Alkaline Properties Test Reaction
  lattice, the dehydrogenation of rings appears to be related to
  transition metals.
  In conclusion, most of the metal oxides studied possess acidic sites and hydrogen
  Accepted sites, i.e. they must be considered members of group A-B
  (according to [3]). Not only metal ions but also basic oxygen atoms have
  Hydrogen acceptability. Simple and rapid conversion of cyclohexanol
  Methods for determining the functionality of oxide catalysts.