We are honored to present this special issue of theChinese Journal of Chemical Engineering(CJChE)as a Festschrift in honor of Professor K.T.Yu (1922.11-2022.4) to commemorate the 100th anniversary of his birth,and celebrate the 40th anniversary of the CJChE,which was co-founded by Prof.K.T.Yu,together with Prof.Chia-yung Chen (Jiayong Chen).

This special issue was originally planned as a tribute to celebrating the 100th birthday of Prof.Yu in this November.To our great sadness,however,Prof.Yu left us on April 6 this year.This makes all of us more mindful of Prof.Yu and his great achievements in his lifetime.

Prof.Yu got his undergraduate degree from the National Southwestern Associated University in Kunming,China in 1943,and received his M.S.and PhD degrees from University of Michigan in 1945 and University of Pittsburgh in 1947,respectively.Then he became an assistant professor at University of Pittsburgh and his early contribution to Chemical Engineering were papers on thermodynamics and mass transfer-based separation.He returned to China in 1950 and was appointed as professor of Chemical Engineering Department in Tangshan Engineering College of North Jiao-tong University before he joined Tianjin University in 1952,where he served as Professor,vice-head of Chemical Engineering Department,director of Chemical Engineering Research Center,honorable dean of the School of Chemical Engineering and Technology of Tianjin University,technical director of State Engineering Research Center of Distillation,and was elected as academician of Chinese Academy of Sciences in 1991.

In his career of more than 70 years,Prof.Yu dedicated himself to the research and education in Chemical Engineering and became a top-rank influential pioneer in Chemical Engineering in China,particularly in mass transfer and distillation separation engineering.He was involved in drawing up the first ‘‘Chinese Twelve Years Long Term Scientific and Technological Development Plan” in 1956,initiated the first national distillation research program in China under the framework of the above plan,organized his team and founded the first distillation laboratory in the late 1950s,marking the startup of basic and industrial oriented research on distillation in China.In 1960s,the research achievement under his leadership in ultra-precise rectification and associated process dynamics found successful applications in a number of national key sectors urgently needed at that time.He pioneered the idea of research on fluid dynamics for large column trays,and established an industrial scale column in his laboratory for experimental investigation.As one of fruitful outcomes of this research,he proposed,in the early 1980s,a number of models of mass-transfer considering the maldistribution of fluid flow on trays or in packings,aimed at handling the non-equilibrium and non-total mixing issues in distillation process simulation and design.

Prof.Yu orient persistently his research to industrial applications.A number of innovative technologies were developed by his team not only for tray columns but also for the advanced structured packing columns,which have been continuously improved and successfully applied to thousands of industrial distillation columns in chemical,refinery,and petrochemical plants in China.Such achievements,contributing significantly to the Chinese economy,led to profound changes in Chinese process industries and played an extremely important role in industrial separation operations,energy saving and emission reduction.

Prof.Yu’s successes in applied research are rooted in his firmly founded basic research.He was one of the few who started to tackle the complex problem in distillation from ever fundamental aspect in the world.He introduced the laser holographic interferometer to investigate the concentration distribution in immediate vicinity to the gas-liquid interface and laser particle velocimeter(PIV) to get insight into the interfacial turbulence phenomena.He proposed to develop turbulent diffusion equations of species in the fluids in trays or packings and to incorporate the diffusion equations into the fluid dynamic equation system so that it can be solved for the first time by CFD (computational fluid dynamics)packages for the species concentration distributions.Such attempt enabled more reliable estimation of separation efficiency of a distillation column by scientific computation with mush less experimental correlations,allowing using more scientific methodology instead of relying on traditional experiences in the design.Prof.Yu referred such advanced methodology to as‘Computational Mass Transfer’and authored a book with the applications to not only distillation,but also absorption,chemical reaction,and others by Springer in 2014,and another one with more applications by Chemical Industry Press Co.,Ltd.(China) in 2017.Prof.Yu’s fundamental research in the mass transfer,one of the most common phenomena,shed light on many basic processes in Chemical Engineering operations including chemical reaction,material preparation,biochemical engineeringetc.

Prof.Yu was a great organizer of scientific research.He founded the Chemical Engineering Research Center at Tianjin University in 1982,and created a model for industrializing the research results of his team by providing a spectrum of services,from basic investigation,design,manufacturing,site installation,to operational starting-up.It was such an industrialization model that supported the fluent streams of research achievements from his laboratory to thousands of industrial distillation columns.He founded the distillation laboratory of the ‘‘State Key Laboratory of Chemical Engineering”,which is engaged in fundamental research,the National Engineering Research Center for Distillation,designed for engineering development of distillation technology,and the National Advanced Column and Internal Technology Promoting Center,composed by a number of column internal manufacturers for promoting industrial applications of new technologies.As such,a comprehensive frame for distillation technology research and development,from fundamental research to industrial application,has been established in China.

Prof.Yu was a passionate educator.He wrote the first textbook for teaching undergraduates the precise distillation and process dynamics in early 1960s.He was the tutor of over a hundred of graduate students for master and doctoral degrees.He was commissioned by the Ministry of Education to lead two important projects of education reform for the chemical engineering undergraduate education:‘‘Research and practice of talent training scheme and reform of curriculum system for chemical engineering specialty” (1996-1999),and ‘‘Research and implementation of the reform of teaching content,teaching method and teaching technology of innovative talent training mode for chemical engineering specialty” (2000-2003),participated by nine Chinese universities.

As one of the co-founders and co-editors-in-chief of the CJChE from 1993 to 2011,Prof.Yu,together with co-founder Prof.J.Y.Chen and many contributors,reviewers and editors,made his utmost efforts for the growth of the journal,laying solid foundation for making it from a domestic English journal of Chemical Engineering to an internationally influential journal with its steadily rising impact factor.

It is our hope that the publication of this special issue will deeply cherish the memory of Prof.Yu and his life dedicated to the chemical engineering discipline and chemical industry in China.And we wish the Chinese chemical engineering community prosperity under the inspirations of his spirits.

We have received 47 contributions and 42 were selected for publication in this special issue.The subjects of the research papers in this special issue cover wide spectrum of the Chemical Engineering areas,from fluid dynamics,separation science and engineering,catalysis and reaction engineering,to process systems engineeringetc.Four review papers contributed by leading scholars are included.

We would thank the authors offering their excellent works to this special issue.Thanks also go to those who have submitted their contributions but not get published finally in this special issue because of the limited space.We appreciate all the hard work from the staffs of the editorial office of the CJChE to make this special issue published.