.contenedor{
width: 100%;
margin: auto;
overflow: hidden;
}

#sliderinfi {
width: 4600px;
height: 120px;
background-image: url("../images/demo.jpg");
background-size: 100% 100%;
animation: sliderinfi 15s infinite linear;
}

@keyframes sliderinfi {
  to {
      background-position: 2000px;
}

}