## 3 Results and Discussion
### Corrosion Inhibitors  
The results found for group A descriptors (corros* and (inhib* or inib*)) were very productive for the international databases, with 25,407 articles from the Web of Science, and 43,100 and 36,454 patents from Derwent and Orbit, respectively. These figures reflect the concern of the academic and industrial scientific community to mitigate the effects of corrosion in several fields and places.  
Figure 1a shows the distribution of these documents over the period evaluated (2011 to 2020). There is a very significant growth in the number of patents in 2016 at Orbit as well as in 2019 at Derwent, presenting 2051 and 3285 deposits, respectively. On the Web of Science, there is a continued growth in the number of published articles, although the number of patents remains higher. This fact may be directly related to the oil industry, for the development of these products internally or for the external production to be offered to this segment, as it is one of the industries that suffer most from economic losses caused by corrosion. For example, in 2014, China spent around USD 310 billion and it is estimated that around USD 1372 billion is spent annually due to problems related to corrosive processes in the oil sector [30; 31].  
The largest holders of these patents are petrochemical industries. China Petroleum & Chemical Corporation is the largest depositor, with 568 and 596 records at Derwent and Orbit, respectively. Corrosion in this branch can generate direct and indirect costs associated with the loss of time, replacement of construction materials and continuous involvement of personnel in this management, in addition to environmental and safety consequences.  
Figure 1b presents a comparison referring to the Brazilian scenario, with peaks in the PTO in 2014 and 2017, with 17 patent deposits each year. At SciELO, the peaks occurred in 2016, 2017 and 2019, with eight articles published each year. When comparing the two sources, the number of patents was only lower than years 2012 and 2020.  
Finally, when comparing Figure 1a,b, the quantity of patents and articles is much lower in the specific searches for Brazil in relation to the international scenario. This demonstrates that the representativeness of the country is still discrete in corrosion inhibitors.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Group of** & **Descriptors** & **Web of Science** & **SciELO** & **Derwent** & **INPI** & **Orbit** \\
**Descriptors** & & & & & & \\ \hline A & Corros* and (inhib* or inib*) & 25,407 & 79 & 43,100 & 231 & 36,454 \\ \hline \multirow{3}{*}{B} & Corros* AND (inhib* or inib*) AND & & & & & \\  & (green OR environmental sustainable OR & 2263 & 7 & 989 & 10 & 632 \\  & eco-friendly) & & & & & \\ \hline \multirow{3}{*}{C} & Corros* AND (inhib* or inib*) AND & & & & & \\  & (green OR environmental sustainable OR & 333 & 2 & 22 & 0 & 20 \\ \cline{1-1}  & eco-friendly) AND plant* AND extract* & & & & & \\ \hline \end{tabular}
\end{table}
Table 2: Quantitative numbers of articles and patents recovered with the combination of descriptors in Table 1 in the databases of Web of Science, SciELO, Derwent and INPI.