Metal catalysts supported on biochars: Part I synthesis and characterization

•Some new paragraphs have been added to the manuscript in order to clarify some points raised by the reviewers.•Conclusions section has been improved following the requests of referee 3.•Some typos, errors and pictures have been fixed.•The position of Fig. 1 has been corrected as proposed by referee 2.•Two new acknowledgements to scientific projects have been attached in the acknowledgements section.