Thermally evolved gases from thiourea complexes of CuCl in air: Detailed comparisons by TG-FTIR and TG/DTA-MS for compounds poor and rich in thiourea

J. Madarász, Malle Krunks, Lauri Niinistö, G. Pokol

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6 Citations (Scopus)

Abstract

Detailed identification and monitoring of gaseous species released during thermal decomposition of two thiourea (tu) complexes of CuCl, one of them, Cu(tu)Cl 1/2H2O (1) poor, while the other, Cu(tu)3Cl (2) rich in thiourea, have been carried out in flowing air atmosphere up to 800 °C by both coupled TG-EGA-FTIR and simultaneous TG/DTA-EGA-MS. The thermal decomposition of 1, prepared actually from CuCl, has shown evolution of similar gas mixture and dynamics by TG/DTA-MS, as had been measured with TG-FTIR and published earlier, except that no evolution of ammonia has been detected, at all. Probably, the intense co-evolution of acidic vapors (HCl and SO2) has prevented NH3 to reach the ionization chamber of the mass spectrometer. While in case of anhydrous 2, Cu(tu)3Cl rich in thiourea, between 180 and 240 °C, the main gaseous decomposition products are ammonia (NH3), carbon disulfide (CS2), and isothiocyanic acid (HNCS). At about 250 °C, gas-phase exothermic oxidation of CS2 and HNCS vapors occurs, resulting in a sudden release of sulfur dioxide (SO2), carbonyl sulfide (COS), and hydrogen cyanide (HCN). Also a definite evolution of cyanamide (H2NCN) is observed just above 250 °C. Between 350 and 500 °C, a more intense oxidation process of both organic condensed residues and copper(I) sulfides into copper(II)-oxo-sulfates appears, which is also indicated by intense evolution of CO2, SO2, and H2NCN (and/or HNCO). Above 700 °C, the oxo-sulfates start to decompose resulting in repeated evolution of SO2. All species identified by FTIR gas cell have been also confirmed by mass spectrometry. Evolution of HCl from Cu(tu)3Cl (2) has been detected by either of the two EGA methods.

Original languageEnglish
Pages (from-to)189-199
Number of pages11
JournalJournal of Thermal Analysis and Calorimetry
Volume120
Issue number1
DOIs
Publication statusPublished - Apr 1 2015

Fingerprint

Thiourea
thioureas
Differential thermal analysis
thermal analysis
Gases
air
Air
gases
Ammonia
Sulfates
thermal decomposition
ammonia
sulfates
Pyrolysis
Cyanamide
Vapors
cyanamides
Hydrogen Cyanide
vapors
Carbon Disulfide

Keywords

  • Copper sulfides
  • Copper(I) chloride
  • Coupled TG-EGA-FTIR
  • Coupled TG/DTA-EGA-MS
  • Evolved gas analysis
  • Simultaneous TG/DTA
  • Spray pyrolysis
  • Thiourea

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Condensed Matter Physics

Cite this

@article{4707909be2a44c8aaf8cc1d86d53c0a0,
title = "Thermally evolved gases from thiourea complexes of CuCl in air: Detailed comparisons by TG-FTIR and TG/DTA-MS for compounds poor and rich in thiourea",
abstract = "Detailed identification and monitoring of gaseous species released during thermal decomposition of two thiourea (tu) complexes of CuCl, one of them, Cu(tu)Cl 1/2H2O (1) poor, while the other, Cu(tu)3Cl (2) rich in thiourea, have been carried out in flowing air atmosphere up to 800 °C by both coupled TG-EGA-FTIR and simultaneous TG/DTA-EGA-MS. The thermal decomposition of 1, prepared actually from CuCl, has shown evolution of similar gas mixture and dynamics by TG/DTA-MS, as had been measured with TG-FTIR and published earlier, except that no evolution of ammonia has been detected, at all. Probably, the intense co-evolution of acidic vapors (HCl and SO2) has prevented NH3 to reach the ionization chamber of the mass spectrometer. While in case of anhydrous 2, Cu(tu)3Cl rich in thiourea, between 180 and 240 °C, the main gaseous decomposition products are ammonia (NH3), carbon disulfide (CS2), and isothiocyanic acid (HNCS). At about 250 °C, gas-phase exothermic oxidation of CS2 and HNCS vapors occurs, resulting in a sudden release of sulfur dioxide (SO2), carbonyl sulfide (COS), and hydrogen cyanide (HCN). Also a definite evolution of cyanamide (H2NCN) is observed just above 250 °C. Between 350 and 500 °C, a more intense oxidation process of both organic condensed residues and copper(I) sulfides into copper(II)-oxo-sulfates appears, which is also indicated by intense evolution of CO2, SO2, and H2NCN (and/or HNCO). Above 700 °C, the oxo-sulfates start to decompose resulting in repeated evolution of SO2. All species identified by FTIR gas cell have been also confirmed by mass spectrometry. Evolution of HCl from Cu(tu)3Cl (2) has been detected by either of the two EGA methods.",
keywords = "Copper sulfides, Copper(I) chloride, Coupled TG-EGA-FTIR, Coupled TG/DTA-EGA-MS, Evolved gas analysis, Simultaneous TG/DTA, Spray pyrolysis, Thiourea",
author = "J. Madar{\'a}sz and Malle Krunks and Lauri Niinist{\"o} and G. Pokol",
year = "2015",
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language = "English",
volume = "120",
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journal = "Journal of Thermal Analysis and Calorimetry",
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TY - JOUR

T1 - Thermally evolved gases from thiourea complexes of CuCl in air

T2 - Detailed comparisons by TG-FTIR and TG/DTA-MS for compounds poor and rich in thiourea

AU - Madarász, J.

AU - Krunks, Malle

AU - Niinistö, Lauri

AU - Pokol, G.

PY - 2015/4/1

Y1 - 2015/4/1

N2 - Detailed identification and monitoring of gaseous species released during thermal decomposition of two thiourea (tu) complexes of CuCl, one of them, Cu(tu)Cl 1/2H2O (1) poor, while the other, Cu(tu)3Cl (2) rich in thiourea, have been carried out in flowing air atmosphere up to 800 °C by both coupled TG-EGA-FTIR and simultaneous TG/DTA-EGA-MS. The thermal decomposition of 1, prepared actually from CuCl, has shown evolution of similar gas mixture and dynamics by TG/DTA-MS, as had been measured with TG-FTIR and published earlier, except that no evolution of ammonia has been detected, at all. Probably, the intense co-evolution of acidic vapors (HCl and SO2) has prevented NH3 to reach the ionization chamber of the mass spectrometer. While in case of anhydrous 2, Cu(tu)3Cl rich in thiourea, between 180 and 240 °C, the main gaseous decomposition products are ammonia (NH3), carbon disulfide (CS2), and isothiocyanic acid (HNCS). At about 250 °C, gas-phase exothermic oxidation of CS2 and HNCS vapors occurs, resulting in a sudden release of sulfur dioxide (SO2), carbonyl sulfide (COS), and hydrogen cyanide (HCN). Also a definite evolution of cyanamide (H2NCN) is observed just above 250 °C. Between 350 and 500 °C, a more intense oxidation process of both organic condensed residues and copper(I) sulfides into copper(II)-oxo-sulfates appears, which is also indicated by intense evolution of CO2, SO2, and H2NCN (and/or HNCO). Above 700 °C, the oxo-sulfates start to decompose resulting in repeated evolution of SO2. All species identified by FTIR gas cell have been also confirmed by mass spectrometry. Evolution of HCl from Cu(tu)3Cl (2) has been detected by either of the two EGA methods.

AB - Detailed identification and monitoring of gaseous species released during thermal decomposition of two thiourea (tu) complexes of CuCl, one of them, Cu(tu)Cl 1/2H2O (1) poor, while the other, Cu(tu)3Cl (2) rich in thiourea, have been carried out in flowing air atmosphere up to 800 °C by both coupled TG-EGA-FTIR and simultaneous TG/DTA-EGA-MS. The thermal decomposition of 1, prepared actually from CuCl, has shown evolution of similar gas mixture and dynamics by TG/DTA-MS, as had been measured with TG-FTIR and published earlier, except that no evolution of ammonia has been detected, at all. Probably, the intense co-evolution of acidic vapors (HCl and SO2) has prevented NH3 to reach the ionization chamber of the mass spectrometer. While in case of anhydrous 2, Cu(tu)3Cl rich in thiourea, between 180 and 240 °C, the main gaseous decomposition products are ammonia (NH3), carbon disulfide (CS2), and isothiocyanic acid (HNCS). At about 250 °C, gas-phase exothermic oxidation of CS2 and HNCS vapors occurs, resulting in a sudden release of sulfur dioxide (SO2), carbonyl sulfide (COS), and hydrogen cyanide (HCN). Also a definite evolution of cyanamide (H2NCN) is observed just above 250 °C. Between 350 and 500 °C, a more intense oxidation process of both organic condensed residues and copper(I) sulfides into copper(II)-oxo-sulfates appears, which is also indicated by intense evolution of CO2, SO2, and H2NCN (and/or HNCO). Above 700 °C, the oxo-sulfates start to decompose resulting in repeated evolution of SO2. All species identified by FTIR gas cell have been also confirmed by mass spectrometry. Evolution of HCl from Cu(tu)3Cl (2) has been detected by either of the two EGA methods.

KW - Copper sulfides

KW - Copper(I) chloride

KW - Coupled TG-EGA-FTIR

KW - Coupled TG/DTA-EGA-MS

KW - Evolved gas analysis

KW - Simultaneous TG/DTA

KW - Spray pyrolysis

KW - Thiourea

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U2 - 10.1007/s10973-015-4481-8

DO - 10.1007/s10973-015-4481-8

M3 - Article

AN - SCOPUS:84939933418

VL - 120

SP - 189

EP - 199

JO - Journal of Thermal Analysis and Calorimetry

JF - Journal of Thermal Analysis and Calorimetry

SN - 1388-6150

IS - 1

ER -