Is there any way to use Laravel Eloquent in the Silex microframework?

You can use yes, as the illuminate / database repository itself, it is actually possible to use it independently of anything, or you can probably use it in any framework, the only dependencies is to install via composer and have php5.6 +, ie this will work for both Silex and anything equivalent.

Type in the terminal within your project composer require "illuminate/database" , if you use the events you also need the command composer require "illuminate/events"

Or set up composer.json (5.4 is the most current version before the development version, you can see other versions):

"illuminate/database": "~5.4",
"illuminate/events": "~5.4"

And then run composer update .

Add autoload.php and call PHP like this:

<?php

use Illuminate\Database\Capsule\Manager as Capsule;

require __DIR__ . '/vendor/autoload.php';

$capsule = new Capsule;

//Exemplo mysql
$capsule->addConnection([
    'driver'    => 'mysql',
    'host'      => 'localhost',
    'database'  => 'database',
    'username'  => 'root',
    'password'  => 'password',
    'charset'   => 'utf8',
    'collation' => 'utf8_unicode_ci',
    'prefix'    => '',
]);

// Define o dispatcher usado pelos models do Eloquent (opcional)
use Illuminate\Events\Dispatcher;
use Illuminate\Container\Container;
$capsule->setEventDispatcher(new Dispatcher(new Container));

// Faz essa instancia de Capsule ficar disponível globalmente usando metodos estaticos (opcional)
$capsule->setAsGlobal();

// Configura o Eloquent ORM... (opcional e desnecessário se você já usou setEventDispatcher())
$capsule->bootEloquent();

This part above you could put in a global file which would be accessible to everyone, or when you call a specific namespace, for example \Model\foo\bar (I'll talk about it later).

After adding the above file, you can use:

• QueryBuilder

  $users = Capsule::table('users')->where('votes', '>', 100)->get();
  

• Schema Builder

  Capsule::schema()->create('users', function($table)
  {
      $table->increments('id');
      $table->string('email')->unique();
      $table->timestamps();
  });
  

• Eloquent ORM (I think this is what interests you):

  class User extends Illuminate\Database\Eloquent\Model {}
  
  $users = User::where('votes', '>', 1)->get();
  

Creating a namespace to use the Models

Now let's say you will not use ORM on every page, there's really no reason to load everything if you will not use it, so you may want to organize your project based on a namespace, I suggest doing something like:

...
"require": {
    "php": ">=5.6.4",
    "illuminate/database": "~5.4",
    "illuminate/events": "~5.4"
},
"autoload": {
    "psr-4": {
        "FooBarModel\": "app/Models"
    }
},
...

This case is an example, assuming you have a folder named ./app/Models within the project.

<?php

namespace FooBarModel;

use \Illuminate\Database\Capsule\Manager as Capsule;
use \Illuminate\Events\Dispatcher;
use \Illuminate\Container\Container;

$capsule = new Capsule;

$capsule->addConnection([
    'driver'    => 'mysql',
    'host'      => 'localhost',
    'database'  => 'database',
    'username'  => 'root',
    'password'  => 'password',
    'charset'   => 'utf8',
    'collation' => 'utf8_unicode_ci',
    'prefix'    => '',
]);

$capsule->setAsGlobal();

$capsule->bootEloquent();

//Cria a classe
abstract class Model extends \Illuminate\Database\Eloquent\Model {}

<?php

namespace FooBarModel;

class User extends Model {}

<?php

namespace FooBarModel\Admin;

class FooBar extends \FooBarModel\Model {}

<?php

require __DIR__ . '/vendor/autoload.php';

<?php

require __DIR__ . '/vendor/autoload.php';

$user = new FooBarModel\User\User;

<?php

use FooBarModel\User;
use FooBarModel\Admin\FooBar;

require_once __DIR__ . '/../vendor/autoload.php';

$app = new Silex\Application();

$app->get('/', function ()
{
    return 'Home';
});

$app->get('/user', function ()
{
    $user = new User;
    ....
});

$app->get('/user', function ()
{
    $user = new FooBar;
    ....
});

$app->run();