Determination of the Blowing Agent Distribution in Rigid Polyurethane Foam

The amount and distribution of blowing agent in rigid polyurethane foam were determined by several methods, which are described and compared. A method for solvent extraction with subsequent gas chromatographic analysis was developed and found to be advantageous for CFC-blown foam along with a combustion method (the Schoniger method), where the chloride ions formed were determined by titration. The solvent extraction method was successfully applied to blowing agents in CFC-free foams as well. Three methods involving heating and weight-loss determination were evaluated. They are easy to use, but corrections for thermal decomposition of the polymer are needed. About half of the total amount of CFC-11 in the investigated polyurethane foams from district heating pipes was found to be dissolved in the polymer matrix

Specific volatile hydrocarbons in smoke from oxidative pyrolysis of softwood pellets

Samples of smoke from laboratory burning of commercial sawdust-based softwood pellets were analysed by gas chromatography on an aluminium oxide column. Flaming burning was very efficient. Significant emitted hydrocarbons were methane, quantitatively followed by ethene and lower proportions of ethane, ethyne and propene. The even lower hydrocarbon emissions from final glowing combustion were strikingly different with ethyne and benzene as the only prominent non-methane hydrocarbons. Smouldering combustion caused much higher hydrocarbon concentrations. Prominent non-methane compounds were furan and ethene from initial smouldering, and ethane, ethene and benzene from after-flame smouldering. The large differences in the proportions of specific hydrocarbons should be considered in evaluations of emissions from residential burning of pellets, with respect to combustion technology and impact on environment and health

Characterization of sixty alkenes in a cat-cracked gasoline naphtha by gas chromatography

The alkene-rich petrol fraction from refinery fluid catalytic cracking (FCC) has been characterized by GC and GC-MS. Quantitative proportions and retention data of 52 acyclic and 11 cyclic C5–C7 alkenes are given. Relative retentions are reported for methylsilicone and aluminium oxide stationary phases as methylene units (MU). Applications of mass spectra, single-ion GC-MS monitoring and retention data for identifications are demonstrated

Life cycle assessment of a catalytic converter for passenger cars

A life cycle assessment of a typical ceramic three-way catalytic converter manufactured for a Swedish passenger car is performed. The environmental impacts occurring in the life cycle of a catalytic converter, encompassing the extraction of raw materials, production of a catalytic converter, use phase, etc. are assessed. They are compared with the environmental benefits assessed throughout an average service lifetime of a catalytic converter. Inventory data show that several significant environmental impacts occur in the life cycle and are related to mining and production of the Platinum Group Elements (PGEs) used as the catalytic elements as well as to the use phase. At the current recycling rate, two of the three weighting methods used in this study indicate that the environmental impacts such as resource depletion and waste generation are not less important than the air emissions reduced at the car exhaust pipe. As its name implies, a “catalytic converter” is a “converter”. From a global and life cycle perspective, the catalytic converter is “converting” rather than reducing the environmental impacts. The results show that it is converting exhaust emissions from one place to environmental impacts in other places of the world. It is important that a life cycle perspective should be used for any “end of pipe” solution and the environmental impacts occurring in the life cycle should not be overlooked and should be weighed against the environmental benefits