With one of the fastest-growing economies in the world, China,
like many countries, faces a growing environmental challenge. The
country’s transportation needs have grown exponentially in Beijing,
a capital of 15 million people.
To avoid the threat of gridlock, Beijing’s extensive network of
bus routes connects the residential suburbs with the city center.
Yet with more buses comes the inevitable decrease in air quality.
China’s widely attended 2008 Summer Olympics, presented as the
first “Green Olympics”, highlighted Beijing’s air pollution levels
challenges, particularly by the global media covering the event.
To stop public transportation from making the situation even
worse and instead use it to bring about a solution, China launched
a completely new approach. The Beijing transport authorities phased
out thousands of older diesel buses and replaced most of them with
buses that meet Euro IV emission standards before the 2008 Olympic
Games. BASF Catalysts took on the challenge of equipping Beijing’s
first mass transit buses with SCR (selective catalytic reduction)
catalysts. By the start of the Olympic Games more than 1,000 new
buses equipped with the new technology were introduced.
Collaborating with Yuchai Machinery Corporation, China’s biggest
engine manufacturer, BASF Catalysts developed a cost-effective
method of applying modern catalyst technology to large diesel
engines used in mass transit.
The SCR system, based on technology developed by BASF Catalysts
years ago for stationary applications (such as power-generating and
industrial manufacturing facilities),lowers nitrogen oxide
emissions in line with strict Euro 4 emission standards – which
became mandatory in China for all new vehicles starting March 1,
2008.
Beijing bus diesel engines were fitted with a so-called SCR
catalyst to reduce harmful emissions of nitrogen oxides. The SCR
system consists of a urea injection system and a downstream SCR
catalyst. A urea solution is injected into the exhaust system
before the SCR catalyst. The urea forms ammonia (NH3) in the hot
exhaust flow, which then converts the nitrogen oxides in the SCR
catalyst, where almost 95% of it is converted into nitrogen and
water.
The catalyst system was carefully tested in engine test
facilities under real operating conditions. Special attention was
paid to the interaction between engine management and SCR system
plus the measurement of emission values. Strict quality standards
were essential because the engines and catalysts are designed to
have a long service life under difficult conditions.
But the ultimate result was many more clean-running mass transit
buses operating on the streets of Beijing. Beijing’s transport
authorities have announced that they will phase out thousands of
older diesel buses and replace most of them with buses that meet
Euro IV emission standards.
Reducing harmful emissions in China is a key task for the
future. BASF Catalysts is already making an important contribution
today. So that Beijing remains mobile and the air becomes cleaner.
It’s a goal worth working hard for.