I am great pleased to welcome you to Beijing and attend the 2015 CAS-TWAS Symposium on Green Technology for Sustainable Development (2015 Green Tech) on July 23-25, 2015. This conference is organized by Chinese Academy of Sciences (CAS), the Academy of Sciences for the Developing World (TWAS), and hosted by CAS-TWAS Centre of Excellence on Green Technology (CEGT) and Institute of Process Engineering (IPE), CAS. The symposium has been designed to provide a comprehensive overview of the latest research developments and technology innovations in green technology for sustainable development, which requires urgent attention from the entire world, especially the developing countries due to the energy crisis and environmental pollution issue. One of the main targets of this conference is to bring together academic researchers in different fields to discuss about the possibility of integration new technologies. In addition, we hope this symposium can help engineering scientists, practitioners, policy makers from the developing countries as well as the developed countries to better communicate with each other. The topics of this symposium will cover a wide spectrum of engineering science, including green solvent and green chemistry, catalytic reaction and process engineering, biotechnology and bioprocess, nanotechnology and materials, renewable energy and green technology, environmental pollution control and other related topics. We are grateful to our sponsors and exhibitors for their generous support and assistance for this conference. I would like to extend our thanks to the all Symposium Chairs, Conference volunteers, and Invited speakers and to all of you who came to present and share your wonderful research work! We also hope and trust that you will enjoy your visit to the very beautiful and wonderful city of Beijing, in July 2015.