Volume 1 [1999]

The activity and selectivity of Pd catalysts supported on YSZ and dosed with different amounts of Na promoter
has been investigated for the reduction of NO by alkenes (C3H6) or alkanes (CH4). It is found that
Na strongly promotes the reduction of NO by C3H6. Rate increases by an order of magnitude are achievable,
while the N2-selectivity is improved from ~75% over the unpromoted Pd catalyst to >95% over the
optimally Na-promoted catalyst. With CH4 as the reductant, a very different behaviour is observed: for all
loadings, Na induces only poisoning. The experimental data indicate that Na increases the strength of NO
chemisorption relative to the hydrocarbons. This is accompanied by weakening of the N-O bond, thus
facilitating NO dissociation, which is proposed as the critical reaction-initiating step. According to this
model the promoting or poisoning effect of Na depends on the interaction strength of the catalyst surface
with the hydrocarbon. The different behaviour of propene and methane reflects the weaker interaction of
alkanes with metal surfaces compared to that of alkenes. XPS and Auger data demonstrate that Na coverage
increases monotonically with promoter loading and that there is no significant tendency for the promoter
to agglomerate with increasing promoter loading. However, a very small but constant tendency to
accumulate subsurface or dissolved Na was observed as the promoter loading is increased.

Chlorination of drinking water leads to the formation of a variety of Disinfection By-Products (DBPs) that may have adverse health effects on humans. Research on this subject has been continued and new epidemiological and toxicological studies have been conducted. This review summarizes factors affecting DBP formation and predictive equations proposed for it, physical and chemical properties, environmental fate, actual measurements of these compounds and technologies for controlling them, as well as regulation and currently proposed changes of their Maximum Contaminant Levels (MCLs) after evaluation by EPA of new data available.

This paper deals with the analysis of atmospheric concentrations of secondary photochemical air pollutants
in Athens for the 11-year period 1987-1997. Photochemical pollution, which seems to be the
most serious air pollution problem in Athens, is originating mainly from the transformation of car
emissions, and its control is a quite complicated task since various non-linear phenomena are implicated.
The main subject of this work is to examine whether the substantial decrease observed in the
concentrations of the primary air pollutants, especially for CO, in Athens in recent years is followed by
a corresponding decrease in the photochemical air pollutant levels in the Athens basin, while the characteristics
of the seasonal and diurnal profiles of photochemical pollution are investigated. In this context,
the interannual variability of O3 and OX (O3 + NO2) is examined for the peripheral stations of
Liossia (10 km northwest from city center) and Smyrni (5 km southeast), which have continuous
records of O3 and NO2 data since 1987. In general, the concentrations of the photochemical pollutants
(especially OX) in both examined stations are comparable, while they seem to have remained essentially
at the same levels since 1990. Further pollution abatement measures should be taken in order to
comply with the EU ozone air pollution standards in the Athens basin.

In recent years, a considerable research effort has been devoted to Life-Cycle Assessment (LCA).
However, most of the work has been focusing on improving the methodology as such and providing
guidelines for carrying out LCA studies. Much less effort has been dedicated to the exploration and
analysis of the applications of LCA within the actual context of business. Which are the drivers for
starting LCA activities in a company? Which are the main applications? Which business departments
are involved? This is the kind of questions addressed by the present paper.
The paper reports the results of a survey about the use of LCA in business in four selected European
Countries, namely Germany, Italy, Sweden and Switzerland. 1600 questionnaires have been sent out to
selected companies in the four countries. As expected, there are considerable differences between
countries because of a different level of environmental awareness. However, there are some main common
results. The first one is that the cultural approach of Life-Cycle-Thinking is spreading out, but not
yet the tool. LCA is not yet used as a routine tool for assessing environmental aspects of product innovation
and it is still rather employed in a retrospective way than in a prospective one. Benefits of LCA
are considered to be rather long-term ones. On the other hand, the large majority of firms is optimistic
about the future use of LCA, most likely linked together with other instruments.