\documentclass[12pt]{book}

% #################################
% ###### Preamble #################
% #################################

\usepackage[a4paper,margin=3cm,innermargin=3cm]{geometry}
\usepackage{needspace}
\usepackage{marginnote}
\renewcommand*{\marginfont}{\sffamily\footnotesize}
\usepackage{amsmath}

\usepackage{imakeidx}
\usepackage{hyperref}
\usepackage[utf8]{inputenc}
\makeindex[intoc]
\usepackage{mhchem}

\newenvironment{conf-abstract}[4][]{
  \needspace{10\baselineskip}
  \begin{center}
    { \renewcommand\textsuperscript[1]{}
      \phantomsection\addcontentsline{toc}{section}
      {\texorpdfstring{#2 (\emph{#3})}{#2 (#3)}}
    }
    {{\large\bfseries #2}\marginnote{#1}\par}
    \medskip
    {#3\par}
    \smallskip
    {\small #4\par}
  \end{center}
}{%
  \bigskip
  \hrule
  \bigskip
}

\usepackage{etoolbox}
\newcommand{\indexauthors}[1]{%
  \forcsvlist{\index}{#1}
}
%\patchcmd{\thebibliography}{\chapter*}[1]{\section*{#1}}{}{}
%\patchcmd{\thebibliography}{\refname}{}{}{}
\patchcmd\thebibliography{\chapter*}{\section*}{}{}

\renewcommand\bibname{\vspace{-2em}}
%\bibliographystyle{IEEEtran}

\setcounter{tocdepth}{3}
\setcounter{secnumdepth}{-1}
\pagestyle{plain}

\let\affil\textsuperscript

\let\oldbibliography\thebibliography
\renewcommand{\thebibliography}[1]{%
	\oldbibliography{#1}%
	\setlength{\itemsep}{0pt}%
}

\begin{document}

% #################################
% ###### Abstract     #############
% #################################

\begin{conf-abstract}
% Title
{
Your title here
}
% Authors
{
N. Name\affil{1},
}
% Afffiliation(s) by use of "affil{#}" and (\\)
{
\affil{1} Department, University/Lab, City, Country 
}
% Presenter: Lastnamename, F.[irst Name]
\indexauthors{{
%Smith, G.
}}

% #############
% Abstract text 


%\small
\begingroup
\renewcommand{\section}[2]{}
\begin{thebibliography}{}
	\bibitem{Reference}
		N. Name \textit{et al.} (2022) \hfill
\end{thebibliography}
\endgroup

\end{conf-abstract}

\end{document}





