Here is a list of online books about Chemical Engineering in various formats available for free :

Advanced Granulation Theory at Particle Level

by Peter Dybdahl Hede, 2006, 62 pages, 6.1MB, PDF

Advancing Desalination

edited by Robert Y. Ning, 2012, 216 pp, 18MB, PDF

Bioethanol: Science and technology of fuel alcohol

by Graeme M. Walker, 2010, 114 pages, 4MB, PDF

Chemistry and Technology of Fertilizers

by Vincent Sauchelli, 1960

Coal Pyrolysis

by George R. Gavalas, 1982, 177 pages, 5.6MB, PDF

Electrically Driven Membrane Processes

by Soren Prip Beier, 2006, 52 pages, 5.4MB, PDF

Electrochemical Methods for Neuroscience

edited by Adrian C. Michael, Laura Borland, 2007

Enzyme Technology

by Martin F. Chaplin, Christopher Bucke, 1990, 280 pages

Fluid Bed Particle Processing

by Peter Dybdahl Hede, 2006, 80 pages, 6.2MB, PDF

Fundamentals of Air Pollution Engineering

by Richard C. Flagan, John H. Seinfeld, 1988, 554 pages, 19MB, PDF

Fundamentals of chemical reaction engineering

by Mark E. Davis and Robert J. Davis, 2003, 17MB, PDF

Fundamentals of Combustion

by Joseph M. Powers, 2010, 410 pages, 3.1MB, PDF

Fundamentals of Reaction Engineering

by Rafael Kandiyoti, 2009, 112 pages, 4.2MB, PDF

Fundamentals of Reaction Engineering – Worked Examples

by Rafael Kandiyoti, 2009, 41 pages, 3.5MB, PDF

Fundamentals of Thermodynamics

by J. Karl Johnson, 2009, PDF

Heat Transfer

by Chris Long, Naser Sayma, 2009, 156 pages, 4.8MB, PDF

Heat Transfer: Exercises

by Chris Long, Naser Sayma, 2010, 89 pages, 6.3MB, PDF

Hydrocarbons

by J. C. Jones, 2010, 111 pages, 3.6MB, PDF

Hydrodynamic Modelling and Granular Dynamics

by Peter Dybdahl Hede, 2006, 42 pages, 4.9MB, PDF

Hydrogenation

edited by Iyad Karame, 2012, 326 pp, 8.3MB, PDF

Introduction to Chemical Engineering Processes

Wikibooks, 2012, 136 pp, 1.6MB, PDF

Mass Transfer in Chemical Engineering Processes

by Jozef Markos, 2011, 306 pp, 13MB, PDF

Methods in Industrial Biotechnology for Chemical Engineers

by W. B. V. Kandasamy, F. Smarandache, 2008, 126 pages, 2.5MB, PDF

Essentials of Nanotechnology

by Jeremy Ramsden, 2009, 126 pages, 4.6MB, PDF

Numerical Methods and Modeling for Chemical Engineers

by Mark E. Davis, 1984, 267 pages, 7.7MB, PDF

Polymer science and engineering: the shifting research frontiers National Academies, 1994, 199 pages, 7.5MB, PDF

Practical Chemistry for Engineering Students

by Arthur James Hale, 1912

Pressure Driven Membrane Processes

by Soren Prip Beier, 2007, 22 pages, 1.4MB, PDF

Process Control Fundamentals

PAControl.com, 2006, 73 pp, 2.2MB, PDF

Process Dynamics, Operations, and Control

by Barry Johnston, 2006, PDF

Science For Coalmining Students

by H. Morton, D. S. Morton, 1952